New MacBook Pro with Mavericks- reformat or not?

Question

Hi folks,
Background:  I had a lovely MacBook Pro running Snow Leopard which died on me and so I replaced it last week with this equally lovely late 2013 Retina 15" 2.3GHz i7 MacBook Pro which, obviously, came with Mavericks.
But since I was under pressure to get work out I actually set myself up on this Mac, using Mavericks, thinking to just drag some of my files from the old MacBook Pro's hard drive (already in a caddy) to "stock up" my new computer with files I needed when I discovered the Migration Assistant and, perhaps, ill-advisedly just migrated the lot.
I have used it fine with only three applications of, quite literally, a hundred or so lost to me and two glitches probably due to "confused" preferences, but I know that having done it this way is not ideal.  I have the original Mavericks based User (hidden of course) and the migrated one.
Snow Leopard versus Mavericks:  I very much like Snow Leopard and I don't actually dislike Mavericks as much as I thought I might.  But if I were to have to choose one OS over the other the one which would save me money would possibly win.
My problem with Mavericks is two-fold:  1. I have Photoshop CS (yes, OLD.  But I cannot justify buying upgrades and it works well for what I use it for) and cannot now run it, and 2.  I MUST be able to run Final Cut Pro (6 but I recently bought 7 finally) on it reliably (and I have never had crashes under Snow Leopard, never EVER, but had already one in just one week with Mavericks, possibly due to the way the application arrived on the machine I realise).
My only problem with Snow Leopard is that it is not as cool as Mavericks but for a video editor that is not the be all and end all of it... 
What I would like help with is:
1.  Could I even have this new Mac run well enough with ancient Snow Leopard (so that I can rescue Photoshop CS)?
2.  If absolutely, categorically now- how do I start over?  I mean- uninstall the migrated User and take the machine to factory settings?  IS it as simple as reformatting (I ask the "silly" question due to the fact that I have not yet worked with a computer which doesn't have install disks) and then reinstalling the software (yes- I have an external hard drive now)?
3.  How to effectively "pick the bones" of the old hard drive (I still have the hard drive in the caddy I can take files from-  it has become a sort of "time capsule" of my old MacBook Pro) so that I don't mess up Mavericks but still get things like my old email, iPhotos and some installed applications which I am not sure I can find the download links for (even though I have my purchased serial numbers they are often not associated with the download website and with so many I am concerned that I might lose some).
Thank you so much for reading. 

Answer 1

MacBraveheart wrote:
Hi folks,
Background:  I had a lovely MacBook Pro running Snow Leopard which died on me and so I replaced it last week with this equally lovely late 2013 Retina 15" 2.3GHz i7 MacBook Pro which, obviously, came with Mavericks.
But since I was under pressure to get work out I actually set myself up on this Mac, using Mavericks, thinking to just drag some of my files from the old MacBook Pro's hard drive (already in a caddy) to "stock up" my new computer with files I needed when I discovered the Migration Assistant and, perhaps, ill-advisedly just migrated the lot.
I have used it fine with only three applications of, quite literally, a hundred or so lost to me and two glitches probably due to "confused" preferences, but I know that having done it this way is not ideal.  I have the original Mavericks based User (hidden of course) and the migrated one.
Snow Leopard versus Mavericks:  I very much like Snow Leopard and I don't actually dislike Mavericks as much as I thought I might.  But if I were to have to choose one OS over the other the one which would save me money would possibly win.
My problem with Mavericks is two-fold:  1. I have Photoshop CS (yes, OLD.  But I cannot justify buying upgrades and it works well for what I use it for) and cannot now run it, and 2.  I MUST be able to run Final Cut Pro (6 but I recently bought 7 finally) on it reliably (and I have never had crashes under Snow Leopard, never EVER, but had already one in just one week with Mavericks, possibly due to the way the application arrived on the machine I realise).
My only problem with Snow Leopard is that it is not as cool as Mavericks but for a video editor that is not the be all and end all of it... 
What I would like help with is:
1.  Could I even have this new Mac run well enough with ancient Snow Leopard (so that I can rescue Photoshop CS)?
2.  If absolutely, categorically now- how do I start over?  I mean- uninstall the migrated User and take the machine to factory settings?  IS it as simple as reformatting (I ask the "silly" question due to the fact that I have not yet worked with a computer which doesn't have install disks) and then reinstalling the software (yes- I have an external hard drive now)?
3.  How to effectively "pick the bones" of the old hard drive (I still have the hard drive in the caddy I can take files from-  it has become a sort of "time capsule" of my old MacBook Pro) so that I don't mess up Mavericks but still get things like my old email, iPhotos and some installed applications which I am not sure I can find the download links for (even though I have my purchased serial numbers they are often not associated with the download website and with so many I am concerned that I might lose some).
Thank you so much for reading. 
CS3 and newer will run, CS2 or older will not.
You can not run Snow Leopard on your machine (unless you run the Server version in a virtual machine)
Erase your Mac, use Setup Assistant and do the migration correctly, start with an empty Mac (like a new one is)
As for FCP, there are mixed reports, some say it will not install but once installed (?) will run OK, you can but try.