Good onya mate with the 8"er,
!
There are two solutions for your finder, one is a right angle finder which has the eyepiece at 90 degrees (I'm not a fan of them, but others swear by them- personal preference) and the other is attaching a red spot finder atop of your existing finder. I did just this for my big dob, attaching a red spot finder to a big finder (see pic). Look here for some good inexpensive gear, in particular Guan Sheng (GSO).:
http://andrewscom.com.au/site-section-10.htm
Their little red spot finder is the one I used, $29 -see pictures.
There are two eyepieces I'd suggest for you that will be a good match for your 8", both from the Guan Sheng (GSO) range;
*30mm Superview $69
*15mm Superview $49
I have both and have used them on an 8" dob too. They are the two eyepieces I most use with my 17.5" dob.
For high power, unless you want to spend more than $120 on one eypeice you won't get to use to much, I'd suggest to just get a 2X barlow, $29. Cheap high power eyepieces are really difficult to use. With your 12.5mm eyepiece you will get 200X magnification, which is normally the highest power you can regularly use, and the 12.5 eyepiece is relatively easy on the eye to use.
I think you will be really well served by these items for a very long time.