Spell cost at character creation

Yes, the same as their level. There is a limit to the level you can get based on your scores. Just stay within those limits and keep the total level of all the spells no higher than your maximum limit (usually 120).

Post gauntlet, it's always almost better to go with the "complex creation" path.

Indeed.

My rule of thumb is that (post-gauntlet) a spell should cost 10 XP, regardless of its level. The char-gen cost of spells doesn't really make a whole lot of sense when compared to the complex creation or in-game rules.