Need to edit 24p .mts files on FCP 5

Hello! I have been looking for answers for days on message boards, but I'm going in circles chasing only "possible causes" and can't find my specific problem, for obvious reasons.

To start: I'm a cameraperson, inexperienced on FCP. I am a very poor student filming with borrowed equipment, trying to edit on what I could afford, at home, so I realize there will be groans about my trying to use a dinosaur program (FCP5) on a dinosaur machine. The answer when it comes to technology is always "buy the new thing, it'll solve all of your problems." I can't, so I need help from anyone kind enough to help:

Trying to make a <23min film, total runtime (shooting at approx 4:1 ratio, so in total I'm trying to keep my footage to less than 90min) .

Using PowerMac G5 1TB main HD (OS 10.5.8) (computer entirely devoted to FCP only, I don't care about file size or time to render etc.), 4GB RAM

I want to shoot (have shot some) 1080/24p FX footage on a Sony AX2000, .mts files.

I chose DV-NTSC 24p (23.98) Advanced Pulldown Removal in setup.

I first chose HD (720x480) NTSC DV (3:2) in Sequence Settings... I see lots of answers to this size in canvas problem are related to matching this up with the imported video.

Because there is no Log and Transfer in FCP5, no way of converting to this "ProRes", I converted the .mts files with iSkysoft to .MP4 (though I'm not sure if that's a conversion with minimal loss. I also tried pulling them in as MPEG2, no audio came in so, wrong again...).

When I brought the MP4s into FC in this manner, they are fine in viewer, tiny in canvas. I can't see what I'm doing over there.

So, I looked at the clips in bin, item properties --->it shows they are only 320x240.

If they are automatically shrunken to edit 24p more quickly and easily, does an editor have to look at a small canvas to do all the edits, then it becomes full quality, regular size when it gets exported, presumably to quicktime?

I just want to bring in files and know that what I've edited, what I'm looking at, is pretty accurate to what others will see in a presentation like powerpoint, then can be uploaded to a site similar to youtube.

If I cannot edit this 24p, could someone describe to me an alternate recording format which can be more easily accomodated in FCP's preferences? If I should use another recording format, what easy setup do I choose for it and what sequence setting matches it?

Thank you so much