CPU upgrade

Hello,

I just bought a optiplex 990 with i3-2120 LGA 1155 cpu.

Motherboard has two sets of numbers.

1st one is: E93839

2nd one is: KA0121

Don't know which is motherboard is ID.

Took a chance and bought a i7-2600 LGA 1155 cpu on offer up.

I will be installing Windows 10 Home bought from ebay with new product key.

My question to you are:

1) Is that i7 compatible with that motherboard? I know it fits socket but I read some cpu's might still not be compatible.

2) Do I need to update BIOS and where can I find that update?

3) If question 1 and 2 are ok to go. Do I install new cpu first then new Windows 10 or vice versa?

4) Anything else you could think of I should know?

Thanks