The Xindi do appear to have disruptors like the Klingons. They are also [obviously] advanced in weapons technology (i.e. "the Weapon").
I get the distinct impression, however, that the Xindi are not particularly widespread... indeed, it seems that they've never left the Delphic Expanse (except to attack Earth).
Regarding why the Xindi always seem to dock and board when attacking enemy vessels, I've always thought that it was either a.) because polarizing the hull somehow affects their transporter technology, b.) they can't send over more than one or two people at a time (limiting the effectiveness of boarding parties), or c.) they prefer the physical act of boarding enemy ships. Sure, maybe they could use their transporters to board, but isn't it more fun to climb through that airlock and blast the first homeotherms you see? :D
Like I said, I'd guess they do have warp drive technologies, but that the subspace corridors are faster for their travel needs. I'd also guess that their impulse drives are pretty good, considering that they can outrun Enterprise in STL pursuit.
I don't think we've seen Xindi missile weapons of any kind thus far, but that doesn't mean they don't have them; their disruptors just do the job pretty well (as "the Weapon" seems to indicate).
I think that they possess standard sensors, particularly due to some comments Degra made about Enterprise having sophisticated sensors for a warship. I took that as a sign that their sensor technologies are fairly similar.
I haven't noticed any universal translator technologies amongst the Xindi. It seems that they all understand each others' languages. I'd say that the Primates, Arboreals, and Reptilians all speak Xindi Standard, while the Insectoids and Aquatics both speak their own languages (though, as I said, they all understand each other).
The Primates, Arboreals, and Aquatics seem to make use of cruisers, while the Reptilians prefer warships and the Insectoids, fast attack cruisers and [perhaps] transports (for their spawn). They also all seem to use shuttles and escape pods, too. How would you classify Degra's vessel? Scout? Science vessel?
And finally, "the Weapon." How would you build something like this? How big is the damned thing anyway? It seems to be considerably bigger than the largest Xindi ships, but how big is that?
mactavish out.