1. Someone with more technical knowledge is going to have to field this one as far as the difference between abralon and siaair.
2. I get them from a seller on ebay: "bowl300300". $20 for 5 pads and you can specify what grits you want. Most bowling supply sites charge $8-10/pad even at bulk prices. Since I only use them for my personal equipment, I don't go through them enough to buy them in bulk.
3. Only 6 uses seems like a short life span but idk. Depends on the grit I guess since the courser grits tend to smooth out quicker it seems. I usually just rinse them out as well but maybe someone will have a different method.

1. Someone with more technical knowledge is going to have to field this one as far as the difference between abralon and siaair.

There is no real difference in use, Both pads use the Fepa "P" scale
Siaair is aluminum oxide and abralon is silicon carbide.
Siaair pads last longer than abralon when both are used properly.

Note: there is now "P" scale wet/dry paper available. While the backing would be different, it is alternative which can be cheaper

2. I get them from a seller on ebay: "bowl300300". $20 for 5 pads and you can specify what grits you want. Most bowling supply sites charge $8-10/pad even at bulk prices. Since I only use them for my personal equipment, I don't go through them enough to buy them in bulk.

Supergrit.com has some good prices

http://www.supergrit.com/products/products_discs-abralon.asp

Abralon
$3.50 / 1
$16.25 / 5
$60.00 / 20

3. Only 6 uses seems like a short life span but idk. Depends on the grit I guess since the courser grits tend to smooth out quicker it seems. I usually just rinse them out as well but maybe someone will have a different method.

this is not wrote in stone, your mileage may vary but...

Abralon pads last about 10 balls and Siaair pads last about 20 balls. (You could then mark them as the next higher grit and use for the same amount then toss them.)

And Thank You for your response Sir! Would you also recommend just rinsing them with water? Or do you advise an alternative cleaning method?

Of course you would rinse them out, you don't want buildup in the pad.

Make sure to check if the grit spec on the ball is Fepa(European) or ANSI/CAMI(American)

A lot of older balls use the ANSI/CAMI spec.  I believe Brunswick was also one of the last manufacturers to adopt the use of the Abralon Fepa grit pads. 
When it says Abralon or SiaAir it uses Fepa.  I think when it says something like 1500 "grit" , a lot of times it is ANSI/CAMI. It could be either though. You would need to check with the manufacturer for clarification.

Check out the grit comparison chart on the lower link. Some good info.

http://en.wikipedia.org/wiki/Sandpaper

http://home.earthlink.net/~litefrozen/downloads/bowling_grit_chart_v2.pdf

I wish bowling web sites would follow normally sanding/abrasive conventions.

If you're specifying ANSI standards, nothing precedes the grit level; e.g. 360 grit.
If you're specifying FEPA standards, a "P" precedes the grit level, e.g. P1500 grit.

If you don't do this, you leave yourself wide open for trouble and misinterpretation!!! and the user remains confused.

Abranet uses the FEPA standard just like Abralon. Abranet discs don't have the foam backing. They appear to be mesh or "net" like.  The weave varies depending on how course or fine the grit rating is.

Abralon may be the same thing stuck to a piece of foam.  I don't know.

check this out.  I don't know how I found it but it looks like it is the info you are looking for

http://www.abralonpads.com/Products/40-powerhouse-abranet-soft.aspx

A revolutionary new finishing process at Ebonite International, includes a 1500 grit step, using the 1500 grit Abranet® pads. In order to refinish bowling balls to factory specs.

Developed from Aluminum Oxide with a nylon backing, Abranet® pads will remove more stock from the ball, with less damage to the surface vs. conventional paper. Aluminum Oxide particles make the Abranet® pads more durable and give a less smooth finish than the Abralon® pads. The thin nylon backing makes the Abranet® pad more aggressive, so this product should only be used on a tabletop ball spinner. Applied by hand using the Abranet® Sanding GlovesTM, you’ll have that ball back to its factory finish in no time, prolonging the life of the ball!

as far as what the manufacturer posts as its grit process.
i will put mine on the spinner before even throwing it.
that way i can duplicate the surface that works for me
IMO, there isnt any difference you will be able to see at 800 vs 1000 grit pad
i use 500,1000, 2000, 3000, 4000 (bought a few 1500)
thats plenty to pick from.
i use a wire brush to clean my pads, works pretty well
dont be afraid to try different surfaces, the OBB surface is pretty much a starting point as far as im concerned

Stop drinking the Kool-Aid and just by a quality wet/dry sandpaper for 1/10 the cost.

It's been many (many) years since I've used wet/dry sandpaper. Is there really no effective difference from using Abralon??