To your second and third points, if you have a drill/driver with a torque setting, use that and turn the torque right down before running screws into MDF.

(The torque setting is the numbered collar behind the chuck on your driver, if it has one. It won't be calibrated to anything, but lower numbers mean less torque applied to the fastener before the driver stops turning it.)

A low torque setting vastly reduces the hazard of splitting the MDF, or chewing up the bolt's drive socket, if you're a little careless on the trigger. Then you can hand-finish with a regular driver.

I'd hesitate to use a thread locker on Ikea bolts. They're cheaply made and very mild, so it's hard enough to get them out without stripping the drive as it is; there's no way you're going to break Loctite and not end up needing to grab a bolt head with vise grips. (And that's if you break the Loctite before the drive strips. I wouldn't count on that.) At most, I'd say wait until you know there's a problem with a fastener backing out before you start thinking about gooping it up with something, and even then probably start with something less aggressive than even blue Loctite - a tiny dab of superglue, maybe.