Sculpting with a mouse is doable, but not adviseable.
So if you have the possibility to get a tablet do it it's worth it.
And regarding the blobby look;
It's probably because your brushsize is to small and has a high fall of aswell this way you get that " blobby" look
Why don't you try ZBrush?
I use both and my findings are that Mudbox is easier when it comes to importing OBJ's from Maya, with ZBrush I always have to go back and forth to get it right, Mudbox also doesn't complain when it comes to triangles, but when it comes to sculpting i dislike Mudbox;
-Displacement maps are next to impossible to get right there's no quality control and when in Maya it doesn't seem to have a lot of detail
-interactively adjusting the strength of the brush is impossible it snaps right to 1 or 2.5 and when you work with 0.300 values you have to put away.
-Painting color on a model is irritating since you paint on the uv's and sometimes when youpaint the back of a model it somehow projects through the model on the front so you have adjusted the texture there too.
Painting color with ZBrush has the same issues but a lot less and you can choose between painting on geometry or painting on UV's(proj.master)