well horns and teeth are very similar, the grow out and are not apart of the skin so making them separate to the main model but parented would make a more realistic look. Also yay for blender ~ <3

plus say you're going to do something drastic, like he gets mutated, having horns separated will make the modeling easier x3

I'd hit it

It depends on what you're doing with it. In the end, you'll most likely want some kind of indication it is connected with the body(possibly a cuticle of some soft) so it doesn't look as though a spike is run through the body. In that case, having it separate or not wouldn't mater as it would be hidden by that cuticle. But as a general case, i wouldn't go out of your way to connect things if there's a logical disconnect (ie, a hard edge, seam-line or intersection of some sort).

Also, don't be afraid of triangles :) You can always add a loop and remove them later, but 80-90% of the time they're not as big of a problem as you'd think.

The new Blender's interface is a lot more intuitive.

Looking good so far. Wish I could give you some advice, but my current knowledge of 3D is pretty limited.

The way the head is shaped doesn't look like it gives enough room for the brain to grow...
Or at least to me.

Very cool thus far, tis' coming along nicely!

it'll look fine with separate meshes dont fret brah

O LAWD, avoid separate meshes where possible! They will obviously not be part of the same mesh when seen in closeup under armature animation because an arbitrary interpolated point on the horn won't ever have the same bone weights as the basemesh under it. It'll slide around ("look fake"). This won't be a problem with, say, the center thigh horn, because it'll be affected only by the upper leg bone, as will the skin under it. But the upper horn is going to get weight from both leg and hip, and that one will slip around like a motha, rise out of the skin, etc. under armature animation. This is an extreme example, but e.g. this eyebrow implant looks terrible when animated http://www.furaffinity.net/view/4081357

If you need an edge to look sharp, select in in either vert edit or edge edit mode, use ctrl-e to mark it sharp, and use the Edge Split modifier with Sharp Edges checked and Edge Angle unchecked to prevent the normals from interpolating across it.

The topo around the mouth could use some work, and you'll want to add some edge rings on the tail to get the faces square-ish. Personal preference, shin looks short compared to foot.

To disagree with DotMatrix, be afraid of triangles, on organic forms/curves, if you are going to subsurf or sculpt. I don't know if Blender handles them worse than other tools' subsurf algos, but if your model is going to get a high-poly render with good lighting, I can almost guarantee you'll notice them later, after you'll have to throw out work to fix it.

Crits aside, it's coming along really awesome and I'm always glad to see good 3D work around here

Oh dear.
I'll somehow have to, like, remake everything just to have space for each horn then. Without making too many tris.
Why is there no lazy way out that also looks good?

I'm probably being overly spooky about it. I'm pretty compulsive about "following the rules" and take too much time doing so. The best way to learn it is to try it and see what goes wrong. It would just take a minute to make a temporary two-bone armature, one at the hip and one at the femur, auto-weight everything to it, and see how it looks under deformation. I suspect you'll see what I was talking about. It'll be partially managed with heavy manual tweaking to the weights, but I think not not ultimately fixable.
If you're not planning on doing closeup HD animation it may well not be worth the effort to join the meshes. Everything's a tradeoff!

If the tradeoff is me going a lot more insane during rigging than normal later vs me getting the base done a bit slower now then I know what I'll pick.

Not having proper weights seems to be down to user error and has nothing to do with separate meshes. Arbitrarily merging meshes just to keep a contiguous mesh is bad practice as it add unnecessary complexity to the mesh. Do what you need to do in order to keep it organized and workable.

Also, triangles do cause issues with subdivision, but not so much as you make them out to be. what causes issues mainly are pinch points, which triangles can cause easily (which is why people say triangles are bad). In this example, there are more n-gons and skewed quads, which are even likelier to cause a pinch and fuck the subdivision. In general you want as even a topology as you can get so that each polygon is roughly similar to those around it.