1. Correct syntax is
UseCode:self giveWeapon( "weapon_name", 0, false );
to give max ammo.Code:self GiveMaxAmmo("weapon_name");
2. No idea what you're talking about.
3. Here's list of some, if not all, killstreak names.
Code:killstreak_uav_mp killstreak_helicopter_mp killstreak_ac130_mp killstreak_predator_missile_mp killstreak_helicopter_minigun_mp killstreak_nuke_mp killstreak_precision_airstrike_mp killstreak_counter_uav_mp killstreak_sentry_mp airdrop_marker_mp airdrop_sentry_marker_mp killstreak_helicopter_flares_mp killstreak_emp_mp airdrop_mega_marker_mp killstreak_stealth_airstrike_mp killstreak_harrier_airstrike_mp