I’m sure everyone has slightly different view on this and it also depends on what your financial conditions and your goals are (note: I’m not a qualified financial advisor so always consult one when in doubt).
401k has a penalty for early withdrawal usually 10% (if you withdraw before retirement). You can possibly take a loan out of the 401k if you need to. My companies has “no strings attached” policy to it’s 401k offering so I can take it out any time I want. Check with yours.
IRA is your own account so you can do whatever you want with it. Check with your IRA broker what policies they have.
Roth and regular (401l and IRA) differs on when you get taxed on it (i.e., now per contribution or lumpsum after retirement).
Based on my research and heresay it seems US markets are always more profitable to invest in than other markets. If I had to choose I’d keep my retirement funds here accumulating either in 401k or IRA (say, after I leave my job here), unless I really needed it. I would be investing in US stocks anyway and these accounts give a significat ROI. Now, I haven’t actually tried closing any of these so I’m not sure if there’s any physical-presence-requirement in the US to keep these accounts open.
Now if you had to transfer money to Canada from your regular bank account you can do a simple wire transfer to your Canadian bank through SWIFT, and your institution has their own amount limits and fees per transaction (e…g, $10,000 limit and $35 per transfer). You can also take a cashiers check across physically, however, last time I did that it took 21 days for it to clear . So cashiers/travelers checks recommend only if you don’t mind waiting. You can also carry any amount of cash, but if it’s over CAD$10,000, you’ve to declare it and they’ll let u bring it in tax-free.
First thing you do after arrival is go to the local Service Canada (not Service <Province-name> but Service Canada) office and get your Social Insurance Number (SIN). Then go to a bank and open an account. If you’re staying longer you can also hunt for apartments etc and look for jobs.