3a.
There are a great many possible answers here, of course. Here's one:

1 A020 power
2 A119 P0
3 A218 P1
4 A317 P2
5 B016 P3
6 B115 P4
7 B214 P5
8 B313 P6
912 P7
10 ground11

3b.
One good answer is: You can't really combine multiple copies of the above chip to make larger multiplications, at least not in an easy way. In the case of multi-bit adders, any number of 4-bit full-adder chips can be combined to make a 4n-bit full-adder, by just connecting the carry-out from one to the carry-in into the next. Multiplication doesn't work this way.

(There are other possible answers too.)

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