Your file share will take the map however it is when you upload it and keep it that way, so if you make changes you must delete the odl one off it and upload again.
Note, however, that it is far wiser to use the Save As feature than the Save feature. There is a very prominent glitch where, when using the Save feature, the last map you have been on is overwritten. Using Save As at all times will never result in this, though you may want to add a number to the end of each new save so as to remember which is the newest (example: Map 1.0, Map 1.1, 1.2, etc...)
Another way to avoid this is to "Clear the cache." This is done by simply, before loading up the map you plan to work on, you load a dev map beforehand. A lot of people use Abandon, as it is at the top of the list. These methods should help save you from losing a map you've put hours into, which has happened to almost all of us once or twice.
As for FFA, any gametype that can support FFA should have the options "Teams: Enabled/ Disabled" in it's gametype options. Slayer, regicide, king of the hill, and oddball are the most notable FFA modes.
Good luck!
