Need formulas for accounting spreadsheets

I have a few questions for a spreadsheets program I am creating...
Explaining what it does, specifically in reference to my questions:

Worksheet A
COLUMN 1C COLUMN 2D $ COLUMN 3E
Check Written To (John), Categories (Supplies), $100.00
Check Written To (Sam), Categories (Materials), $100.00
Check Written To (Joe), Categories (Supplies), $20.00

Worksheet B
COLUMN 1J $ COLUMN 2K
Category Added Amounts from $ above
Supplies $120.00
Materials $100.00

What I need to figure out are the formulas for these questions:

Referencing Worksheet A only
1) Can I make a formula that automatically places the category
(based on the information typed into Column 1C) into COLUMN 2D?

{
I'm limited in my formula skills, but I want something like this, knowing it is ridiculously wrong and it's probably not even an IF THEN statement...
IF(my variable, is true, not true)
=IF(C5=Wcompany, D5=Materials, no idea for false part
C5=Pcompany D5=Towing, false part
C5=Ycompany D5=Parts, false part
etc, etc)
}

Referencing BOTH worksheets
2) Can I make a formula that automatically adds the (example: "Supplies") and inserts the totals from Worksheet A column 3E into Worksheet B Column 2K (like I did above in the sample)?

formula in cell below column 2K -
{
=SUM(Total of "Materials" from Worksheet A Column 3E)
}