That's a good choice for the first foray back into the classic machines, for the most part they're very reliable. Getting one with a network card is a stroke of luck, there aren't many of those floating around for the compacts anymore.
On the SE you should be okay, they aren't nearly as susceptible to capacitor failure as the SE/30 and later machines.
I would skip trying to network the SE straight into a newer PC, while it's cool to be able to say you've done so, it's a lot of hassle and requires an intermediary machine running an older version of Netatalk. To my knowledge HFVExplorer doesn't work with physical SCSI devices, but I may be mistaken. I've had the best luck with a newer Mac acting as a bridge machine. Early G3s seem to be at the bottom of their value curve and will play nicely with newer machines while still directly interfacing with the older ones (and are much easier to set up than a linux box running Netatalk IMHO).
SE accelerators don't seem to pop up all that often and when they do they're on the higher side. I would think you'd do pretty well if you decided to sell the network card.
A lot of people on "everyone's favorite auction site" seem to think old = rare and valuable, which is usually not the case but at the end of the day all the stuff is worth what others are willing to pay for it. I wouldn't worry about the cover for the battery holder. Unless you really jostle the machine the battery shouldn't pop loose. Smart to replace the battery though, there's a thread on here for what can happen if you don't and it's not pretty.
Sssshhh! Most of the public is still brainwashed into thinking new Macs are somehow better than PCs despite being built with identical hardware and (in some cases) Windows actually running better on the older ones than OS X.
Joking aside, I think a number of people on here have a similar mindset. Everything I'd like to run tends to be on the PC side of things and since many Macs starting with the 2013 models are disposable, throw away machines (non-upgradable) I really don't see myself buying a newer one. With that being said, not being able to upgrade a machine is not a deal breaker for everyone and they can be quite reliable machines, if a bit on the expensive side. Different strokes for different folks.