Rick in the USA.

I think I've got my transportation sorted. I'll arrive at LAX, then take the Amtrak train to Oceanside and stay there for the night. The following day, I can take a bus all the way to UCSD. That works out to be the cheapest way. Seriously, taking the bus all that way is $2. What the hell kind of sorcery is that? It's so cheap.

In regards to money, still haven't had a chance to go to the bank and ask their advice.

It is cheap, but with good reason. Bear in mind that you'll be on public transit in LA of all places...Just make sure and keep everything close to yourself and all of your easily concealable valuables on your person for safe keeping. Fortunately transit from OceanSide to UCSD should be more or less a straight shot. If you input your starting point on GoogleMaps and UCSD as your destination you can get your bus route from Point A to Point B, too. I'd assume no more than 2 or 3 transfers; possibly only one even.

I'm pretty sure most traveler cards are Visa these days, so you should be fine in that respect. Most (99.99%) of the places in Orange County take debit cards, so I wouldn't worry too much about it. ALTHOUGH, you will need exact change for your bus fare, which I believe is $1.25 in LA, so maybe get like five dollars in singles if you can. I'm not sure how withdrawing money from ATMs will work in your case though, so you might want to try and bring at least $20 in assorted bills just in case.

Hope that helps :3