Yes, your brake fluid will be 'DOT' ... it's the number following it that's relevant.
The older DOT4 is a fluid based around glycol; the newer DOT5 around silicone. The two will not mix so don't go there.
Silicone is known to attack some older style rubber components - that is why Tim has made the valid suggestion of swapping seals.
Personally if you're just interested in bleeding rather than a complete brake system overhaul I'd say you should stick with DOT4.
I wholeheartedly endorse the Gunson's Easibleed. For little expense this saves a lot of effort if you're doing this on your own.
My only other tip is put penetrating fluid on the bleed nipples a good 24 hours before you think of doing this job. It's all too easy to round off the bleed nipples' small 'hex' profile - or worse 'sheer' off the nipple completely. You will then have to resort to drilling it out. Not wanting to scare you ... just passing on hard won experience!!!