Is it true that uspto reviewers are not responsible for searching out infringements on prior patents and that all infringements are settled in the 'marketplace' .....where it is then determined who's patent was first?
Yes, it's true that the USPTO does not consider infringement of any patent.
Whose patent is first generally doesn't matter. The test is whether the scope of protection claimed by the patent application covers anything already known (as of filing or date of invention) or any obvious variation of anything known. Thus, "prior art" is not limited to other patents but includes all publications.
Trying to determine whether self searching for prior patents, issued or pending is adequate or whether paying our attorney 1500 is wise money spent.
"Adequate" is a business decision, not a legal one. You can never eliminate all risk. However, a little bit of pre-filing analysis can do a lot to remove uncertainty in going forward. Additional reductions of uncertainty follow a curve of diminishing returns, each little bit of uncertainty being smaller and smaller and coming at higher and higher prices.
Somewhere along that line, you reach a point at which further reductions in uncertainty are not worth the incremental cost. When you reach that point, you either proceed with the patent application or drop it and go do something else. "Money well spent" is always a business decision, not a legal one. A practitioner can help you fill in some of the variables in your cost-benefit analysis, but the ultimate decision is a business one.
....and as per this. Do attorneys have access to any search engines beyond the public uspto portal?
Yes. Google.com. Libraries. Some will have access to professional databases of trade publications, such as IEEE. Other patent offices around the world have search portals as well.
Regards.