Garett Seeba, DMD, MD

Absolutely not. For a molar you need a full sized implant.  Otherwise you end up with a "tomato" on a stick and long term this will absolutely fail. Traditionally molar implant widths are 5-6mm just to give you an idea.  Mini implants are 1.8-3mm. 

Immediately loading dental implants is tricky.  Occlusion can play a factor but whoever placed it should account for this.  I would suggest that when it is replaced they use a traditional 2 stage approach (which is what I favor for most cases anyway). 

Hi, 

It sounds like you have peri implantits. The treatment for this is often crown removal, debridement of area, possible bone grafting.  I suggest you get an X-ray of the area as soon as possible and then proceed from there. 

The best way to address this is orthodontics followed by veneers. It is possible to do it all with veneers or crowns but nothing is better than moving your own teeth to their ideal position. Yes it takes longer but it will be more stable and better long term for you. 

Yes extractions are an additional fee. As far as grafting it depends usually it will be required to some degree to get the best final outcome for the implants.