I have an imported mountain bike that I want to get it back on the road, it has a broken rear axle and I will be replacing it with a new wheel, but I am trying to learn more about Bike mechanical too.

The sticker says Shimano 18 speed but I am not sure why there is a 7 speed freewheel in the back. I identified the tool to use to transfer over the Shimano freewheel should be Park Tool FR1 (12 spline).. Do they sometimes put a 7 speed freewheel even though the shifter is only for 6 speeds (3x18).

I measured the frame to be 5 5/16" which translate to 135mm, and I will be looking for a 135mm spacing wheel.

Check the dropout alignment BEFORE putting in a new wheel. 5-10 minute job at the LBS.

=8-)

Why not only replace the axle? It's such a simple job that even if you have to have a lbs do it the end sum is likely to be less than a new wheel. Besides, as already suggested, it'd provide a nice opportunity to have the dropouts checked.

And no, parts are not routinely mismatched. But 7-speed freehubs seems to be more common than 6-speeds, so someome probably slapped on what they had after a previous failure to get the bike back on the road as fast as possible again. If you have friction shifters it's a non-issue. If you have indexed it might not run cleanly.

Hi, I looked into replacing the axle (cheap), but the cap on non drive side come off easily and the bearings fell out, I don't see any seals, skewer is bent, I can still find the parts on biketooletc.com.
but I remember the rear brake bind fairly loud every revolution, so the wheel is not just a little out of true and it is bent.

The shifter is just a lever, no clicks, there are numbers and an arrow but I never look at it very much. Can I just get any Shimano 6 speed freewheel if I want to do it "right"? Other than that I don't know how to check for freewheel wear, the freewheel doesn't have any in/out play that I can tell.

Is there some way I can do a dropout check on my own Without the tool? At least get a rough idea? It's a steel frame.
I don't even have a car and my bike is missing 1 wheel to go to the LBS

If you get a new wheel get one with a freehub instead of a freewheel. The freehub is much stronger.

I found the axles and bearings and will be attempting to replace it first.
since the axle is broken and I have nothing to spin it on, I cannot tell how much the wheel is bent

so my question now is how much can a shop true up a wheel through spoke adjustment?
Seems like the combination of replacing the axle, skewer + truing cost the same as an cheap replacement wheel.

I didn't spend alot of money on this one so try to keep the cost low, it will be my backup bike.

There's really no telling. If it's all down to spoke tension being off, then just about any rim can be saved.
Trouble is, wheels usually end up untrue as a combo of spoke tension + rim damage. And even something like 1/2" of sideways throw by rim damage is really hard to save through trueing alone - spoke tensions become too different for the wheel to be reliable.

Actually, the economics are worse than you describe. I find good MTBs wheels cheap all the time, bought a set (attached to a bike) for $5 at a garage sale Saturday, included wheels, tires, cassette, tubes, etc........ It is not unusual to find used MTB wheels for $5 to $10 each. Since you are starting with a low cost bike, I would hunt for a donor bike or a cheap set of used wheels.