Please do the reasearch, you can find basic physical properties on the Wikipedia  Yes the BP is 98° C.

You don't have to boil heptane, I usually immerse a beaker in a hot water bath (80° C) while mixing with a rod, then decant the liquid in a Pyrex dish. When pouring/decanting, the solvent usually gets milky immediately so I can see it is supersaturated. After few pulls, it does not get milky and the total amount of solvent is some 40 ml per 1-2 grams of DMT.

Pre warmed dish is good so the product does not crash out too soon. I don't mind since I warm the dish a bit on a hotplate, then let cool slowly.