Take the back wheel off by fiddling with the derailleur after you have released the hub. Releasing the wheel and hub is done by unscrewing the axle or by releasing the quick release mechanism. That is more normal and you will find a kind of lever attached to the axle. Loosen the quick release lever by pushing or pulling it away from its fixed position, it then becomes floppy instead of tight. Then install the tyre and reposition the wheel.
Remove tire, remove tube. Buy better rim strip. Install better rim strip. Install tire half way. Repair or buy a new tube. Install tube, Finish installing tire. Inflate tube. Stick wheel back in bike. Check the brakes/chain as needed. Go ride the bike.
If it's a road bike it's probably the approximate width of the tire.
It helps to cushion the rider against the uneven road surface !
hump it
Can be a road bike, a Tri bike, a TT bike or a track bike.
MAYBE - , frame size has nothing to do with tire size. Style does, and if its a mountain bike, it will not work with a 27 (road racing) wheel and tire. Brakes will not fit.
The standard or stock tire for this bike is 140/90-15. A tire that is 165/80/15 is probably the largest you can fit on this bike. If you install a tire that has a wider thread your cornering and turning may suffer and the bike may become dangerously unstable.
Someone can purchase bike tires for road use from Canadian Tire. They have knowledgeable staff that are able to help you with your purchases. Their information is excellent.
It depends what use the bicycle is put to, it may be a racer, a road going tourer or an off-road mountain or trail bike. All have very different tires.
If the bike is set up properly, with a real fixed hub, then you should be able to do it. Keep in mind that the contact patch on a road bike is quite small, and that you're likely to wear your tire out quickly.
Can be quite a difference there, from 400-500 grams for an XC tire to almost a kilo for a wide DH tire. Narrow road bike tires can be even lighter.
That's not so easy to answer, as there's no guarantee that the bike still has the original tires. If it has any tires on it's usually printed on the tire sidewall what size it is. I'll post a link with info on rim / tire combos.