1. At least Class 1 LS
2. Needs pixel-scaling
3. At least
14,700 tons
4. Get the distance between the 2 furthest points of the Colosseum (181.45 m according to google), then divide the distance value by 2 to get radius and dump the value into the ground-based explosion formula. You're gonna get roughly 60.016 tons of TNT (City Block level)
5. Apparently a standard forest according to FAO must contain
1.24 acres worth of 5 meter tall trees. Prolly convert that to meter square, then use some tool to get the explosive radius to put in any explosion formula.
6. Depends on size and depth of lake
7. Prolly should ask Jasonsith, I remember him having made a chart about it.
8. Prolly 10-A to 9-C since compound crossbow arrow-heads can cleave through it like butter, they usually have the capability to piece some body armor designed for .357 Magnum rounds. Depends on armor plating tho. Toughest armor layers (Armor layer level 4) are designed to stop armor-piercing 30-06 caliber rounds.