What are the chances of a woman getting pregnant, even though she had her tubes tide over 2 yrs ago? If she does conceive, would she able to tell?

Low!! The chances of becoming pregnant after having tubes tied is usually less than 1-3%. A pregnancy test would still work just fine after a tubal ligation to detect a pregnancy. If pregnant, you need to see your doctor very early on in the pregnancy to make sure it is in the right spot. You are more at risk to have an ectopic pregnancy which could be very dangerous.
Unlikely. However, very high if you have a tubal reversal. The pregnancy rates after a reversal are very close to never having had a tubal ligation following a reversal.
~2%, see ob/gyn ASAP. Cumulative failure rate after tubal ligation (btl) is about 1.85% during 10-yr period, w/some slight variation depending on method of btl. Pregnancy symptoms may be similar to her previous pregnancies. However, most important is that if she misses her period, do a pregnancy test, and if pregnant, see ob/gyn immediately to rule out an ectopic pregnancy, which is potentially life-threatening.