[Mobhack]

For point 3:

Infantry experience (skill) level is the most highly relevant. Low skill/morale is bad. Elites are best. Your conscripts will do less well than your guards, unless they have gained experience over a campaign.

Infantry that have suppression - bad. Try to rally away any before attempting the assault. If pinned then cannot assault anyway. But every suppression point you have is bad in assault.

Infantry has a good HEAT anti-tank weapon - best. (Grenades least good except if AFV has 0 top armour). An AT-rifle is less useful than an RPG-7. Warhead size of weapon used is also influential - e.g. satchel charges have a decent WH size and HE pen. Flame attack weapons are extremely good for assaults - flame can bypass any armour, even of say a Maus...

Infantry that have moved then try an assault - bad. You could charge 4 hexes down a road and attack with your remaining 2 MP (introduced a few years ago - need 2 MP remaining to assault) but its not the best idea. Best not to have moved at all - so best assault target is any enemy AFV that has put itself alongside one of your infantry, or your guys have camped out beside it since their last turn, unobserved.

Infantry that is not spotted - good (ambush bonus).

Infantry section is large (~4 man poor, 12+ better). Other than dedicated inf-AT classes who have an edge in assault over ordinary infantry and so dont have the small team deficit. Engineers are nothing special over infantry - they just tend to carry kit that makes big bangs *larger W/H size, HE pen) or have flane attack bonuses.
NB - Crews, HQ, snipers have a deficit in assaults (the old SSI sniper as a tank killer went a decade or so back!).

Infantry with damage - less good. Every damage point carried is bad, depleted squads are best not used unless in extremis. Ties in with the point above - the damage reduces manpower and counts against the depleted squad.

AFV with open tops (or sides etc) - very good (grenade buckets!).

Tanks that are buttoned or worse - good. Can be worth your while having another team shoot at it till its buttoned before you assault - especially teams with light mortars which have a larger W/H size than bullets do, so are more likely to pin or possibly even send into retreat an AFV target. Light mortars may even manage a disabling track hit. Routing AFV have poorest inf-assault defence chance other than open-topped ones.

Tanks that have been immobilised (track hit) - better chance. (So a routed AFV that has been immobilised, and is open-topped would fare poorest if swarmed by a horde of grunts).

AFV has low experience and/or morale (conscripts etc) - fare poorer than experts of course. Less chance of rolling a good defensive result, less chance of spotting any potential assaulters, more chance of being in buttoned or worse status due to events.

AFV (or APC) carrying an infantry team can defuse the assault. APC which protect the crew are better than tanks which have to carry them as riders. Tank riders suffer higher casualties. As well as defusing attacks (usually taking damage as a result) on some occasions the infantry can dismount and shoot the failed assaulter in the face. Small teams provide less protection than larger ones of course, a tank carrying a sniper will have less defence chance than if it was a 10 man full-sized rifle section. Tank riders with higher experience and morale work better than a bunch of raw conscripts. The cure for tank riders is of course to hose down any potential targets with rifle or MG fire before assaulting, so they dismount damaged and in poor morale (hopefully!).

Multiple assaults of course can work much better than just the one. If the first team fails, but you rally it up again for a second go may do better especially if the first assault made the tank go into retreat or rout, disabled a track or whatever. If several rifle teams are attacking then it can be a sticky situation for the enemy tankers.

Even if you dont kill a tank with an assault you can make it retreat away - opening up rear shots for any supporting armour or AT guns.