Questions regarding: Input Mask, sum outcome and 2 if-clauses

Hey guys,

for my boss I'm creating a excel file. I have no clue about excel, but parallel to this thread I'm looking for answers to my questions.

The spreadsheet should serve as an overview for different building sites my boss manages. I have attached a screenshot how it's looking right now.
Lgx43.png

1. Is the name of the building site
2. Is the name of the company
3. Date of the bill
4. Delivery/service
5. netto sum
6. date of money transfer

So here are my questions:

1. If I set the date into 6 (date of transfer), how can I automatically display a green tick in the H row?
2. Date of transfer can never be before date of bill, can I get an error message if I try to input that?
3. How can I get the whole sum in the end red if negative, green if positive? <-- read this somewhere before, probably really easy
4. I want to create an input mask where I just enter alle the information and excel sorts it by company, then by date etc. Seems to be a bit harder, do I have to learn VBA for that?

Will post more questions later. If I found something about my questions I'll update here.

Thanks for any help in advance