For the reroofing cost see the many prior responses in Home > Roofing in Browse Projects at lower left for typical costs and discusiion of issues.
As Upgrader said, in almost all cases raising the ceiling is VERY costly, plus involves opening up the interior of the house to exterior weather risk for some days, so you are trusting a lot in the contractor's tarping talents and hoping severe weather does not hit during that timeframe, and especially hoping he does not go belly up or leave you hanging in the lurch while the roof is off.
Raising the ceiling involves one of several methods, none of which are simple:
1) cutting the roof free and jacking it up and holding it in that position (or even lifting it off with a crane), then adding a spliced-on section to the wall, and putting the roof back on,
2) with some types of roofing framing that cannot take being cut free of the walls, cutting the entire upstairs free at the floor level and jacking/lifting that up while splicing new longer studs into the wall to raise it (which also involves electrical and maybe plumbing lengthening too),
3) or removing the roof piecemeal and either raising the walls and rebuilding the roof framing and then putting on the finish sheathing and roofing, or with some designs installing raised-knee trusses that stand up off the wall (3 feet+ in your case) then putting on a new roof and then a new ceiling.
None of these are cheap - would be unusual to get for less than $8-10,000 range for just raising/reframing the roof and in many cases can be 2 times that much, and could be significantly more than that if the entire walls have to be lifted too, as a VERY ballpark range. This is a VERY unusual thing to do if you are talking raising the upstairs ceiling height - adding a new story or raising only the roof to provide attic living space is not that uncommon, but raising the upstairs ceiling height is extraordinary. Most people would not consider spending that kind of money just to gain some headroom, unless you are talking raising the roof to give attic living space headroom, in which case that is more normal to do.
In pretty much all jurisdictions you are ging to need detailed plans from an architect or structural engineer to get a permit to do this, so as Upgrader rightly suggested start there - and he/she can also provide conceptual cost estimates for the work and comparisons of the options. if just raising the roof a structural engineer can probably handle it - if raising the entire upstairs ceiling height or including other remodel work, then you definitely want an architect (who will have a staff or consultant structural engineer do the framing change part of the plans).
My advice - also have him/her rough out the cost for adding a story or an attic living space, because raising the ceiling will gain you little if anything in usable living space or resale value for your money, whereas adding another floor or attic living space will add some square footage and living space for your investment. Also, in some cases, especially in frostless areas where slab on grade foundations are viable, adding an addition with the same square footage might be nearly comparable to the cost of raising the entire top story or the house (as opposed to attic) and give you a lot more square footage to boot.