1. Yes, but the waypoints are a little more advanced. Along with having flags (such as item waypoint, or weapon waypoint), they also have item names associated with them, such as item_healthkit, weapon_shotgun. This helps the bots locate waypoints with specific items they need better. Grave Bot, in fact, is able to import old HPB Bot waypoints. If they're waypointed well, you just have to run "waypoint update" in the console to associate waypoints with their nearby items, then "waypoint save" to save the new data.
2. Eventually. I've never used metamod, so I'm not sure what goes into making a bot meta mod enabled. That's one of the reasons why I released the source, so if someone wants to, they can port it themselves. If I find some free time soon, I'll look into it.
3. While I've always loved HPB Bot, when it comes to actual game play.. the bot just isn't that good. It's never aware of what weapons it needs and doesn't need, or whether it should get more ammo for weapon X, etc. In combat, it simply charges enemies and tries to crowbar them.
Grave Bot is not like that. The bots do keep track of what weapons they have, how much ammo they have, and intelligently seek out weapons they don't have. If you put a bot in a level and let it roam around undisturbed, it will eventually collect every weapon it can (they need to be waypointed), and max out all ammo, along with maxing out health and armor. It doesn't do it by chance either, because it actually knows what to do.
As far as combat goes, they won't necessarily engage an enemy unless they believe it's possible for them to win. This depends on their weapon, armor, and health, and the enemies weapon, armor, and health. If they do decide to 'engage' an enemy, they will track that enemy down via waypoints even if that enemy goes out of site. In close combat, the bots will circle strafe, rather then just run up and crowbar, and if they have the long jump they'll use it to jump around and confuse their enemy.
4. For S&I, there are many features I wasn't able to complete, or rather didn't want to just yet due to time constraints. Bot voting was one of them. I plan to create a dyanmic system which weighs all the technology different amounts depending on the situation of the team. If the team is winning, they'll probably want more defensive techs (more armor). If the team is loosing, they'll want offensive techs (more speed). Getting the bots to vote isn't too difficult (just a matter of them sending a command to the server), it's getting them to vote for the correct technology.