1. What color is the hair?

The hair is a 1b (natural brown)

2. How much does the extensions weigh per bundle?

Each bundle weighs 3.5 oz or 100 grams.

3. How many bundles do I need for a fuller look?

I would suggest 3 or more bundles depending on the style. If your going longer 4 or more because the longer you go the smaller the bundle.

4.) what’s the difference between the silk base closure and lace? 

The difference between the two closures are that the silk base looks more like human scalp and you DO NOT have to to bleach the knots. And the lace is just lace and to get the more natural scalp look you would preferably HAVE TO bleach to the knots.