Yes the spray can resolve. They make it in a trigger bottle too, but I just use the cans.
No, it's not too harsh. I have the beige interior & it cleans it well & doesn't leave any spots or anything.
For the upholstery, I vacuum, spray it on in an even coat - not too much, leave it sit for about 10-15 min, then wipe with a small damp towel in different directions.
For the floor mats, I vacuum, spray on a heavier coat, let it sit about 15 min, then spray any stained spots again. Then I scrub with a stiff bristle nylon brush (like what you'd clean your shower with) & wipe with damp rag.
I think it does a really good job. Only thing I don't like is the smell & this time of year it's hard to leave the car open to air out. I just cleaned the car this weekend & used the resolve on carpets, mats, & front seats, & seat belts. Only thing it didn't clean was the seatbelt & I don't think anything will save it. Looks like it was closed in the door a few times or something. Has a few sections of ground in black. A lot came off & it lightened some, but nothing I've tried & no amount of scrubbing seems to work. Will probably have to just replace the driver's side eat belt at some point.