How many modules of 4-port 1/10 GbE 10GBASE-T copper can be attached at ICX7450?

The 7450 has 3 module slots. Each of those module slots can fit a 4x10GC module. 

So you can get 12 total 1/10 GbE 10GBASE-T ports out of the expansion slots in addition to what you get in the rest of the chassis. 

And at the same time we can have 2-port 40 GbE QSFP+ for uplink or stacking in order to have 2 equipments in teh same cluster?

Regards!

The 7450 has 3 module slots, if there are 2 x 40G modules in the rear slots then there is only the front slot available for a 10G module.

If you have two units stacked using the rear 40G ports then you can put 10G modules in the front slots for a total of 8 10G ports across the two switches.

An alternative configuration would be to put a 4x10GF module in the front and use that for stacking and that would leave space for 2 10G copper modules in the rear of each switch.

There are a few options so I would recommend checking the hardware installation guide as all the details are in there.