US & Canadian tax issue for Korean citizen with Canadian

[echung]

Hi,
I am a Korean citizen with Canadian PR status. I was working in the US from 1999 - Dec 2004 (working on work visa; did not apply for US GC or citizenship); moved to Canada and started new job Jan 2005. I obtained Canadian PR status in 2003 but went back to the US to work. Was deemed non-resident by CCRA for the period I was in the US.
Now, I continue to get income from my US project work (paid on W-2 with all income taxes, social security and Medicare deducted) - this is deposited in my US bank account.
My question:
1) how much credit on my Canadian tax return will I get for the US income taxes, Medicare and social security I paid in 2005?
2) Before coming to Canada last year, I sold some investments and incurred a capital loss, 3000 of which I can claim on my US return. The US alllows youto carry forward this loss indefenitely till it is used up - I still have 20K of losses to use up - can I get credit for these in my Canadian return? If yes, how much credit?
3) What US paperwork do I need to file with the IRS?
4) For my Canadian taxes, do I need a tax pro or can I do it myself using a computerized tax prepare software?

Many thanks,

Elaine