Doesn't look like anyone has given you any help on this yet so I'm unsure if you've already gotten your answers or not.
This varies from state to state, so I will try to fill you in best I can and let you know where you need specific answers for your area.
To answer your first question, you can find most foreclosure information, including pre-forclosure, on county websites now a days. Notice of foreclosures are required by law in any state to be made public (similar to court order appearances) and includes a list of all other interested parties (this is your Lies Pendants to look at who has junior liens, but you will usually need to go to the courthouse to find out how much these liens are for- this is used to determine if you think you should bother trying to purchase the property or if you think a junior lien is going to redeem). You can find these in your local news paper. I always use this as my source for finding foreclosures.
The second question is a little more difficult to answer. You first need to determine for yourself what defines "discount" by your standards. Is it worth it to you to put up 150k on a property which you estimate will sell for 180k....that's for you to decide.
Foreclosures in general USED TO BE almost automatic that there was at least some equity just in the foreclosure price. But with property values dropping a lot of homes are upside down and have negative equity. You absolutely HAVE TO know your market.
Now the last thing that can throw people for a loop- is it a Deed of Trust or a Mortgage???
Depending on which it is may vary the redemption period. Example: Nebraska has a 180 redemption period on mortgages, so there really isn't a rush to buy them at auction when you can just do a short sale twards the end of the 180 days if that note hasn't been redeemed by a junior lien position.
Deed of trust on the other hand has no redemption period in this particular state. Since lenders know this, they virtually do just deeds of trust and not mortgages. But you'll want check to be sure.