If they are minolta autofocus fit then they will fit.

They will all fit the A100, and the first three will give surprisingly
good performance for their age. The Sigma had an excellent reputation
and may well live up to it, too. The Tamron 28-200 is unlikely to be
wonderful.

In terms of coverage, you will cropping the 24 x 36mm frame down to just
under 16 x 24mm, which means losing over half the image area, and a
third of the linear dimensions. That's similar to using a lens 1.5X as
long on the full frame, so the A100 is said to have a '1.5X crop factor'
or a '1.5X sensor'.

So, think of your 50mm as being like a 75mm, your 75-300mm as being like
a 112 to 450mm, your 24mm as being like a 36mm. Just don't say 'my 50mm
becomes a 75mm' or you will get the Real Focal Length police arresting
you for trying to clarify your understanding without regard to
mathematics, optics or syntax. This really gets 'em annoyed.

But, if you want to mutter to yourself, 'let's see, my 35-105mm will be
a 50 to 160mm', and keep this deviation private, you'll find it actually
works that way and you stop being confused.

David

The Minolta's (if they are AF (eg: Maxxum, Dynax)) will work.

The Tamron and Sigma should work, but no guarantee.

There is no conversion to be done.

Or perhaps you meant optical differences?  The sensor is 2/3 the size of
the 35mm film frame (eg: 24x16 mm in lieu of 36x24) so the image will be
 "smaller" on the sensor.  IOW it's as if the focal length were 1.5x
greater.  Not a bad deal except for wide angle.

Cheers,
Alan