Depending on the way you configure the security settings and the options you give web users, yes-- you can allow them to create, modify, and delete database records.
Yes they can also perform searches, and yes-- all can be done thru the browser without them having a local copy of FMP installed on their client.
The quality of your layout representation on a webpage depends on how well you can design webpages-- that is really the limiting factor. You can configure FMP to create PDF files with scripts and send these to users, if print format is really critical you might consider this. Otherwise yes, you are subject to the browser font and size setting specified by each client's browser.
Sounds like FMP can do everything you are looking for.