Wowzers that is commitment, not even got the car yet!

i've done a couple of subframe rebuilds, the hardest bit i've always found was getting the long bolts out as woody says, numbers 11 on this diagram:
http://static.nissan4u.com/epc_img/2518705783274.png
my first car was badly rotten under the subframe, i hope yours is not...
other useful diagrams here:
http://nissan4u.com/parts/sunny/er_n14/1990_10/type_23/
assuming you do not have a proper car lift, getting the subframe down i would recommend:
- driving forward on to ramps and wratchet strap a wheel to a ramp so it doesn't move.
- jack up rear of car using big trolley jack under the rear diff, use a small bit of wood when jacking various bits.
- put axle stands under the car either sills or there's kind of a lump with a hole in it between the sills and subframe mounting point which i find very strong/convenient.
- lower car on to stands, take off and put your rear wheels under the car so if it falls you don't get squashed.(it won't but you can't be too careful)
- big breaker bar and socket set to undo subframe nuts.
- lots of WD40, buy a 5 litre tub off ebay and a spray bottle from poundland.
- get friend to help balence the subframe on trolley jack as you lower it down.
- oh yes, disconnect suspension from hubs, tie with string calipers to the suspension springs, or remove the whole lot...
- undo prop shaft and roll bar end links.
- subframe should lower down, advice would be to undo subframe nuts not quite all the way, lower the jack and if the frame doesn't drop attack it with crow bar, it will drop on to the nuts then take the tension again with trolley jack, undo nuts and lower on jack under diff.
picture for inspiration:

2013-09-21-399 by edward guest, on Flickr
get your fuel tank out whilst you are there and scrub and hammerite car above it, also fix rotten brake lines...

2013-09-22-404 by edward guest, on Flickr

2013-09-22-405 by edward guest, on Flickr
don't paint subframe white, stupid idea, you will turn it black day one with your grubby/greasy/oily hands as you refit it

watch this with regards to pulling bushings:
https://www.youtube.com/watch?v=qhrY7clDIGE
i never used a hole saw but used a length of 10mm threaded bar to pull various smaller sized ratchet sockets with the bushing through significantly bigger sockets (transit van hub socket is pretty massive). the principle is the same, also giant washers, short bit of scaffolding/exhaust tube, use what you can etc.
another example:
https://www.youtube.com/watch?v=0a2mxp-FxYs
you could use a real tool but were's the fun in that!?!?
http://www.ebay.co.uk/itm/Universal-Pro-Pull-Press-Sleeve-Kit-Set-Bushes-Removal-Bearing-Cars-HGV-Tool-/222275711016
i have never fully powder coated frames simply just used wire brush on angle grinder and then hammerite direct to rust paint, dynax s50 inside the hollow bits, including the entire hollow bits of the car. great bit of kit that s50 stuff, comes in a can with a long lance...
http://www.aspo21.dsl.pipex.com//Rust/dynax_can_01.jpg
if you can't be arsed getting the huge bushings out or simply want to save £100 i can supply you with some inserts (and I have most of the rear suspension/trailing/lateral arm bushings brand new for sale, and prop bearing, PM for more info, lets keep this a how-to/help)
if you do want to do the big bushings i would recommend powerflex, make sure you leave the metal ring in place when you remove the original rubber.
http://www.ebay.co.uk/itm/Nissan-Sunny-Pulsar-GTiR-Powerflex-Rear-Sub-Frame-Mount-Bushes-PFR46-109-/222261292356
blow torch is very useful too, i got all bushings out my first frame and arms 100% using fire.
I'm sure a lot of people can provide more pictures and advice.
check your cv joints and boots. inner cv joints rarely go wrong, inner and outer cv boots are very cheap (like £5 each, stretch boots are very good), outer cv joints can be found for £35ish new. Wheel bearings £35ish too.
whilst it is all off the car try and undo your abs sensors from the hubs, maybe soak the hubs in WD40, they are masive pain in the arse rusted stuck f'kers! if they throw up an error code your light will come on and you fail MOT, massive b'stard to undo

Good luck with it all, shout if you want more info!
