1. For me, location is the most important. I would keep your desired location the same. When starting it is best to focus on one location and learn everything you can about it. Your knowledge will make you more confident and able to move quicker and smarter when making offers. But understand that lower income areas tend to cash flow more, higher income areas tend to appreciate more (most of the time). Make sure your expectations of CoC are realistic and find a way to meet them.
2. Most common ways to get in: you can pay more for a property, be creative by going direct to seller, network for deals, find another agent, work with listing agent, become an agent or wait. What fits your criteria best?
3. The fact that you look at so many properties makes me question if you know what you want to buy or if you are truly ready to buy. I may be wrong or just have a different personality. I can look at a property listing, map and pictures to know if I want to make an offer. Pictures can be deceiving, but I know my market and know which properties tend to work best for me. At this point I only go to properties that are priced relatively close to what works best for me. My market is HOT, so if I want to offer 30% below list and fmv, it's probably not going to work out. However, when I see listings undermarketed and underpriced, I move quick. If you like looking at a lot of houses working with the listing agent can be good if you are experienced. But please do not use that agent's MLS access to work with the listing agent directly...unless you want to torch that bridge.
Try different things, figure out what works best for you. And do not feel bad about the situation with the agent. It could have been worse. This business is all about relationships and the fact you're on good terms, they may come back around. And if they don't, keep moving forward.