1) You can choose to have the weight above dwarf size, or just turn civilians off altogether. A lever operated bridge would give you more control though... Providing the dwarves aren't all at a party.
2) Capture a goblin army, danger room train them all to legendary, and release.
3) Candy armour and sharp weapons. Don't make candy shields, crossbows, bolts or war hammers out of them.
4) Candy large serrated discs. Menacing spikes. Maybe a few axes for moar fun.
5) Toady likes to update DF one massive mind fuzzle at a time.
6) Legendary warriors win out right. But having 90 conscripts that have trained for a few years in steel armour is diabolical.
7) If you can't be asked to engrave the walls, use statues and smooth block floors. Or smooth block roads.
Well you don't need to be paranoid about sieges yet, but you should be paranoid about pretty much everything else.
EVERYTHING.9) Put a stockpile that only accepts magma safe stone near his workshop, forbid all non magma safe stone, or make all non magma safe stone economic in the (z) status, (stone) menu.
10) This is DF. If you haven't thrown caution out your incendiary cat bin, you're doing it wrong
11) There's not much point in exploring. Unless you find a crap ton of minerals. Maybe even candy. This one time, I found 4 spires in one.
Hell, now that I think about it, it's well worth the risk of having a few hundred dwarves die.