A: You'd take a little while but you can! Little by little, because if you do it very quickly, you burn the o-ring
A: Yes, it will easily fill a small tire.
A: You'll do best to take the part out and to a local bike shop or even plumbers shop and see if they have something that matches. The shipping cost for trying to order this part (and hoping it fits) is usually not worth it for most bike shops. Last option is checking on either ebay or alibaba.com and seeing if the part can be ordered (probably from china). You will have to measure it in mm and visually look for a match on their site of various sellers. If these options fail, buying a new one is your only choice. The new ones are better built and will last you many years. Good luck.
A: The cost of the new one is less than $20. I would purchase a new one. Five years is a pretty long life for a pump I believe. Hope this helps. Pam