I never noticed these rules. For the PC with a Frost Mace in my main campaign, it just automatically does Cold damage on a hit.It's a free action to activate/deactivate certain magic weapon qualities, such as flaming, frost, etc. A standard action is simply far too much of an investment for those.
This has never come up as an issue for us. No captured giant weapons and the small characters use their own small weapons.I try to keep the 3.0 versions of weapon size scaling (e.g. that Medium-sized shortsword is effectively a Small-sized longsword; none of that "-2 inappropriate size penalty" malarky) and creature spacing whenever possible (no, the giant snake has not coiled up!).
Also hasn’t come up. The only Metamagic feats I’ve seen used are the no-rolling, max damage one (Maximize Spell?), which a Sorcerer used with Magic Missile - automatic 25 hp damage. And the double Duration one (Lengthen Spell?), which was popular with Rope Trick for all night camping.I dump the Heighten Spell feat. I'm sorry, but if you're already casting a spell in a higher-level spell slot, that's punishment enough. You shouldn't need to take a feat to get the save DC scaled up (and spontaneous casters shouldn't have to spend a full-round action to do it).
In general, of the magic feats, Spell Penetration and the Magic Item Creation feats - Brew Potion, Scribe Scroll, Create Magic Arms & Armor, and Create Wondrous Item have all been popular.
Part of this might be the level of play. We’ve never gone above 13th.