the furnace in our home is over 25 yrs old, was thinking maybe about getting it replaced. a few questions,

how much does it cost for a furnace(price range and features)?
where to buy?
installation costs? or DIY?
and rebates or incentives currently offered by companies or government?
how much savings can i expect if i switch to a new higher efficiency furnace?

if i missed anything, lemme know, thanks

v