Using t/con on a macro lens. (1 Viewer)

I've recently got hold of a Kenko 1.5x t/con and thought about trying it on my Tamron 90mm Macro lens.

Will the use of the t/con alter the minimum focus distance and how will the DOF be affected?
For eg. to get more DOF you stop down to f8-f11, however with the use of the t/con you loose one or two stops so does that mean you'll get the same DOF as if you had stopped down to the equivalent aperture with the bare lens?

I'm not very good with explaining technical things so I don't know if you'll understand what I'm trying say, but I'd like to know your thoughts.

Hi Shaggy,
Minimum focus distance will not change.
DOF will be effectively reduced proportionally to that of inverse of mag. factor of TC...
eg...2x TC = 1/2 or (.5 times(front focus to back focus distance))
For example hypothetical apeture that gives 10mm DOF without 2x TC will be reduced to 5mm DOF with.
Do that on occasion with longer focal lengths and extension tubes.
personal favorite is a 300mm F/4 lens,about 50mm of extension and a 1.7xTC,
normally for shooting some large,wary butterflies from about 4 meters.
Give's a bit of a buffer or cushion between critter and I,and gives a magnification ratio that fills frame to satisfaction.
Havent tried on birds,those rascals just too quick.

There's downside too.
Obviously,we know about loss of light...lens speed(even worse with tubes)
Image quality does suffer a bit with the use of any TC...
(An advantage of extension tubes over TC's for macro work)
Aberration at edges begins to show because of magnification.
With big,colorful butterflies attention usually visualy steered away from edges,not so apparent.
If maximum across frame detail is desired,extension tubes might be best option or a flat field TC.

If subject plane is kept parallel to sensor or film plane,yeah its do-able.
If we're trying to shoot a 3 meter long python head on,not much of critter is going to be in focus.