I have an old Trek multi track hybrid that I want to repair to the point where I can use it as a winter beater/commuter bike. Currently, the bike has several issues and I am a novice at bike maintenance/repair.

1. Headset is loose and wobbles slightly. I can probably try taking this apart, clean out the bearings, and tighten everything. However, is it worth it to replace the bearings inside? Where would I even find new bearings?

2. The back wheel tube keeps popping. It lasted for a full year before violently exploding while (thankfully) stopped at a stop light. The replacement tube violently exploded a week after replacement, leading me to think that I probably replaced it wrong and the tube probably pinched against the tire or something. Not entirely sure what happened. I'll need to take a look at the tire to see if any sharp bits got lodged into it causing the tube to pop. I'll also look at the rimtape to see if it's damaged/any spokes poking through. From looking at it currently, rim tape looks pretty new, and tire looks like it's in pretty good shape though....

3. The back wheel became out of true after a car decided to take a sharp turn as I passed by, T-boning me...didn't hurt me, but the back wheel took a bit of a dent. Took it to a LBS who tried to true it but could not do it completely, so trued it to the best of their ability free of charge! Wheel is now OK, wobbles side to side ~1/2 a centimeter. Could the back tube be popping so frequently due to the wobbling untrue wheel at all? Since this bike is old and will be used as a beater, I really don't want to invest in a brand new wheel...

4. Back wheel brake cables somehow got severed...no idea how this happened but I figure I just need a new set of brake cables. Brake pads still have some life, maybe 40%.

5. LBS said the bottom bracket bearings need to be replaced. Not sure what this entails, how to check for signs of wear. What happens if I just ignored this? Would the bike still be functional? (LBS quoted a maintenance overhaul with new bearings, new wheels at around ~$500. NO WAY! I paid less than $100 for this bike!)

The front wheel is old, but works well. Drivetrain works pretty well, almost no corrosion since I cleaned it pretty frequently. Ever since I got a nice road bike, this bike has been sitting in the garage in disrepair for half a year now. Is there any hope for this bike? I'm on a pretty tight budget so I'd like to spend minimal money on new parts. I'm thinking new tube, new brake cable, maybe new headset bearings, that's it.