For an electric guitar I go direct with my (heavily customized) Fender Strat or Les Paul into my Avid Eleven Rack sometimes. Otherwise mic the amp close and offaxis. A Shure SM57 can sound really good and it's really cheap. A chugging rhythm part (something palm-muted on the low E string, generally) at a brisk tempo goes a long way. 140-180 bpm off the top of my head, but there are no rules so whatever works for you.

For drums I often find myself using a straight rock beat. I don't know of any free ones, but there are many affordable ones. Toontrack Superior Drummer 2 is an amazing drum plugin, but it's somewhat expensive and each additional kit is like $100 or so. You best bet for price vs quality is Steven Slate drums Platinum 4 which sounds good and it's like $200 for a ton of good sounding drum kits.

I try to go for a strong melody over the top. Think about old NES and SNES games (or Genesis, I was always a Nintendo guy though); there was often a catchy melody. You can play this in the upper register of the guitar, or a synth, or anything really. Again, these aren't rules, just thought they might help get you started.

Here's an example of a RPG Battle track I made a long time ago with an Electric DI and I think I used crappy SampleTank drums to make it sound a bit more retro.

?

https://soundcloud.com/cch-audio/battle-theme

Epiphone has some humbucker-equipped Les Paul models around $150 that will better suit that style of music. I have a cheap Epiphone Les Paul (a Special II) and it's really not bad. Down the line I recommend upgrading the pickups to something a little better than the stock ones (GFS makes good inexpensive pickups), but even stock I've recorded some good stuff with it. Personally I'm pretty happy with the Eleven Rack, but Amplitube and Guitar Rig are pretty solid. GTR3 from Waves is really good and is only $100 or so. If you can get a sound that you like with a free VST, I'd say go with it. Finally those sampled guitar plugins are fine in a pinch, but you're absolutely right, if you can play guitar and find a satisfactory tone there's no need to go that route.

The Eleven Rack is pretty affordable for what you get. It's about $600 and comes with Pro Tools 12, works as a direct input device with a ton of modeled amps, great for bass and electric. You can even use it in standalone for live shows, very cool piece of gear. The mic pres and the DA/AD aren't the best, but for a home recording setup it's the best in it's price range. Plus Pro Tools is the industry standard DAW so getting that with it is a big plus.

If that's out of your price range, the Focusrite Scarlette is an acceptable interface. It has 2 mic pres/line inputs, the DA/AD is surprisingly good, and Focusrite has a pretty good reputation for build quality. I think it runs around $150.

There interface is going to do a few things for you. First off you have the quality of the Analog to Digital, Digital to Analog converter (DA/AD). Something like a Behringer or PreSonus interface will have a really cheap DA/AD and that's going to affect the quality of your recordings. The second factor is the quality of the mic pres/line inserts. Different pres have different qualities which will color the sound. Something like a Grace pre will be super clean and what you hear is what you get. Where something like a Neve clone will have a low end boost that sounds warmer. Or a Focusrite pre that tends to emphasize the high end making it sound brighter. Those are the 2 big things you're looking for with a home interface. Other factors like the sample rate and resolution are fairly meaningless. Anything at or above 44.1khz/16bit is as good as we can hear anyway, and all interfaces do at least that.

Finally for the last question I use a real bass but I usually go direct in. It can be difficult to mic a bass cabinet and I don't usually want to haul the entire drum kit out of the room just to record bass. Plus bass sounds really good and clean when you go DI and I can take care of getting the sound right in post.