I have a drill wire wheel but I've never used it. I guess if I
polished
or cleaned metal, it could be useful. I can't think of any other use
for
the wire brush; so I wasn't thinking of putting one on the grinder.

CY: As a locksmith, I use the bench grinder wire wheel for taking
burrs off cut keys. I've also found it handy for taking rust off of
tools, etc.

What's a good "grit" for household use for a grinding wheel?

CY: I don't know the numbers, but fine grit works well for most
things. My grinder is from BJ's Wholesale club, from about 1985. I'd
have to look see if I can tell what brand it is. I think it is 1/3 HP.
I use it for burrs on keys, and sharpening t hings like drill bits.

I'd never put wood or soft metal on a grinder wheel - anymore.

CY: Naah, wood is for wood shaping equipment. Grinders also don't do
soft metal. Iron, or steel only please.

In my searches, I saw multi-tool combination grinders with belt
sanders
(1", 2", and 4" belts) which seem ideal for wood. I generally avoid a
tool that tries to do too much because it doesn't do any job well; but
for a grinder, which I admit, is used probably once a month for a few
minutes, maybe a combination tool is usable.

CY: I've never had a belt sander. I'm with you, keep tools simple.

Do people recommend these combination tools?
- Wheel grinder + belt sander (+ some even have disc sanders with
miter
trays).

The combination tool I'm looking at currently has this spec:
- Wheel = 8" x 1 5/8", 60 grit medium
- Belt = 4" x 48" (or 36"), 5300 SFM
- Motor = 3/4 HP, 115/230Volts, 3450 RPM

Do folks recommend combination tools?
What's a good grit if you have only one grinding wheel?

CY: That may work well for you. Since you mention doing wood and
plastic. 3/4 is plenty of HP for most jobs. I'd go with the 115 volt
model, only about 600 watts or so.