I'll try to keep this short, since I don't think anyone has the time to hold my hand for every step...

I have a hard-working 1996 Nissan Sentra GXE. It being as old as it is, and me being as poor as I am, I have to pick and choose repairs based on priority. This month I chose the tires over the exhaust.

So yesterday the exhaust pipe fell off.

I am fairly mechanically inclined, but not trained, and with no experience in cars. I've been doing what research I can, although the search here didn't come up with precisely what I'm looking for.

My specific situation is thus:
Referring to the very useful chart here -
http://www.nicoclub.com/FSM/Sentra/1996/FE.pdf
(mine is page 5)

The front, mostly straight part of the exhaust is hanging loose (well, tied on with a coat hanger). It looks like it broke off the flat piece you bolt it to from the very front, elbow shaped exhaust pipe hidden under the heat shield. I suspect those two front pieces as well as the heat shield will both need to be replaced. The mechanic said (before the part fell off) that it would cost around $300, which probably means it'll cost $400.

My current plan is as such:
1) Purchase wheel blocks or a real jack. Find a very flat place to park (I live on a 10 degree incline).
2) Remove/break the offending pieces (right now I'm at a risk of pieces dragging or tearing off, so I will have to remove pieces before I have the replacement parts, I suspect)
3) Visit the junkyard and buy two new pieces from a 1995-1999 Nissan Sentra. If time allows, purchase the gaskets. Also purchase a new O2 sensor (my check engine light went on - I wonder why)
4)
5) Profit

I'm sort of hoping step 4 will kind of come together as I'm working on it.

Is this reasonable? Without the benefit of blow torches and pipe benders and the like, will I be able to repair this vehicle on my own safely and for less than $400? What do I need to watch out for to avoid being burned/crushed/caught in a giant spinning blade/etc.? Is there anything else I should be doing 'while I'm in the area'? Are there any other resources I should be reading before continuing on? Also, is there anything holding that particular joint to the frame of the car, or is it just hanging there by virtue of being attached to better grounded parts?

Thank you for all of your help!

$300 is absolutely ridiculous. Never visit that shop again. Thats the price of a performance cat back exhaust system.

As for you doing it yourself, you shouldn't have a problem, it's very simple once you have the right tools. On a job like this, I would use ramps, not a jack. You can purchase the plastic ramps at autozone, you'll use it time and time again if you plan to do your own work.
As for the rusty bolts, take a wire brush and clean them off good then spray the bolts with some penetrating spray, keep soaking them for a long time.
When opening them bolts you need to use a wrench on the nut and bolt.

You MUST use new gaskets or you'll have a leak for sure.

Let me ask, there's a scrap yard a few miles away where I can buy exhaust pipes for $6 (but I have to bring my own tools). Would it be a better idea for me to buy parts through them, or buy them new? Can I only take exhaust pipes from '95-'99 Nissan Sentras, or are there other models which will be successful donors?