Yes, Skeletal Wall gets a bonus from Master Summoner (level 1 of each will produce level 18 skeletons). Despite the category it is listed in, Skeletal Wall is still a summoning spell for a non-animal creatures, so is covered by the Master Summoner bonus.
If you save first under a unique name, you can learn skills to try them out, and reload the save if they are not what you thought, or don't fit your playing style. If you wish, you can also make a temporary save, and use
iZakaroN's SaveEditor (or from
Kiya's site, with description) to give yourself extra skill points or experience to try out higher levels of skills than you would otherwise be able to use.
Welcome to the forum.
