Pears, if pruned correctly, are very hardy and can live for decades. There are proportedly espaliad (grown up building sides) pears in france that are over 250 years old. I think for a normal tree, however, 75 years is a good guess, if it is pruned well. (0f course, I think dormant oil is pretty important at the very least)
You should definatley figure out of if your fruit tree is on root stock of its own or not. If it is its own roots, you can simply take green twig cutting, dip them in rootone or some other root growth stimutaly (follow their directions), and have several small trees by fall, for transplanting. If you have to put it onto rootstock, thats a bit tougher. Let me know, if your interested. I'm actually doing some pear cutting from our tree this year, hoping to keep its strain going for the houses future generations.
I love herbs too! I plant Basil, oregano, cilantro, chives, parsly (italian flatleaf is my fav.) ,lavander, dill, and thyme every year. I'd love to try Lemon Balm (love the scent), Anise, and rosemary. I think I may have had a rosemary once....
We also grow peppermint, but only the regular. I've tried the others (there are like 27 flavors) when I lived in lawrence, they had an amazing farmers market. Here in my more rural hometown, not so much variety in anything, and I'm a seller at the farmers market! LOL. We plant mint on the North and East sides of the house, so when the wind blows from those directioins (its very damp in both areas here-the mint is a field almost!) the mint rubbs togather, and the house fills with the most wonder smell. Its a delight to the senses. My grandmother had it there for that purpose, and I'm leaving it for all my days. We go set at the little table in the middle, and walk through the mint growning over the stepping stones, ahh....
I want to plant an herb knot garden!! Or the pie garden, where you make a a circle bed, and divide it like pie or pizza slices, with a differnt hued herb in every slice. I think either sounds great.