For the names, you can't. There is a limitation on them that has not been discovered yet, and therefore, we can't create more. This is the reason why the "create new name" button in A-map is blanked out.
There is a considerable number of map names that are unused...
Ill give a list and tell you how to "Make More"
(this example is based in FireRed, I cannot speak for other games, but its likely a similar situation...)
You can insert any new maps you would like and (using the drop down box) select any of the 12-13 names I have noted above. Then type your new name in the box beside the drop down menu and change its name without hurting the game at all.
If you need "More" names, try getting creative... rename MONEAN CHAMBER, LIPTOO CHAMBER, WEEPTH CHAMBER, DILFORD CHAMBER, SCUFIB CHAMBR, RIXY CHAMBER, and VIAPOIS CHAMBER all TANOBY CHAMBERS, this would use 1 unused name but clear out 7 used names... reworking the naming system is not too hard... but does have its limitations.
You may also try changing THREE ISLE PORT and THREE ISLE PATH to THREE ISLAND then you can reuse those 2 names, this also goes for TANOBY KEY being changed to SEVAULT CANYON but I would change it to "do not show name [00]" this way the NPCs outside that talk about TANOBY KEY still give the player the name, but you can reuse this space... (see creative)
NOTE: just be sure to select the correct ROUTE 4, ROUTE 10, UNDERGROUND PATH and TRAINER TOWER because renaming the wrong one will mess with the ones that use that name (these 4 names are placed twice on the list, ALL instances of them being used in the game use the FIRST listing... the second listing is technically unused)
Note to self: this should probably be a tutorial, its a question asked alot and I have yet to see anyone talk about how many unused names there really are... maybe ill get around to it one day (screenshots and all ;) )