Spend my $
 

My 17" MBP 2.66 Ghz has died. Probably logic board, and I will find out in August when I am in Canada if and how much to fix.
I am stuck using an old 17" iMac to edit a big project, and am dreading the CC and transcode, but such is life, and it is trying really hard. Winning new respect actually...
I am moving back to Canada in December, but will be travelling a lot to Africa for projects.
SO. I am considering on a 5k ish budget:

-fix MBP and also install SSD kit from OWC. It maxes at 4GB RAM, but is there some kit to get around this and maybe get a better graphics card? Maybe eke out a few more years on it?
-get a new iMac or a Mac Pro (6 core?) for the Canada studio. Which one? I run pro tools, edit photos, do animation in Motion, and will likely give FCPX a go... One catch is I currently refuse to rent software, so may be stuck at PS CS5 or 6.
-depending on cost to fix and soup up old MBP, also get or get instead a 13" MBP to travel and ingest footage/basic edits. New or is it crazy to get a used older model for travel and basic video use?

I currently film DSLR and AVHD, but am also watching for a new camera... Maybe 4k as an option... Or an external recorder that gives options. So will iMac be outdated too quickly for 4k, or does it handle it well?
I feel ridiculous that my software stance might keep me away from the macpro for now if the OS won't work for older PS...

Thanks for your input!