Clearly very heavily BF inspired here, not that its a bad thing per say.
Though what I would say for the Medics and MG gunners at least, those seem more gimmicky or counterintuitive to other systems.
For Medics I would inside offer that they be able to, like in BF, run around and revive most* corpses, assuming the leader of that squad they came from is still alive.
*I would set the conditions of none killed via headshot and none killed via fire. If you wanted to limit it more, you could add either bleed out timers to corpses that qualify for revival, or maybe only say a 50% (going up to 90%, via perks) chance of them qualifying for revival. Or maybe favour those soldiers which get killed via a one shot, which would encourage more accurate shooting as well.
For MG Gunners, I would argue against this purely because it discourages you from bringing an engineer for some reason, when its far easier to just build an ammo dump + HMG plus far better for your team. If you do want this, I would instead allow an upgrade for the squad to allow squad members to drop a 1 use ammo box**, carried in their backpack slot. This would simulate an assistant gunner/ammo bearer.
** you could even here just add it as a new item for all squads, where its best used in combo with another soldier using either two weapons or ammo pouches. I think the squad upgrade would work very well with the AT squads too.
Im not against snipers getting those, though I would wonder why you wouldnt just bring an engineer as is and build a rally, honestly just allow yourself to order your AI engineer to build a rally where your standing and that would work just as good.
As for Riders being useful, hell yeah, I never got why they never could do both, I miss the old upgrades for bikes in H&G where you could have panzerfaust boxes on bikes. Maybe allow this but at the cost of the 3rd squad member, so you either get a 3 man squad or a 2 man tank hunter team.