Different Wallets and ScriptSig does it help obfuscation?
The way transactions are associated with one another has to with the transaction's inputs.  When you send bitcoin, you are usually using multiple inputs, each with an address you control.  Anyone looking at the blockchain now knows that the same person controls all those addresses.  Now they can cross reference those addresses with addresses identified as "change" addresses from other transactions, and can be reasonably sure that the inputs to those transactions are also controlled by the same person.  This process can be repeated, which gives is a reasonable guess at which addresses are controlled by a single entity.

A wallet can only combine inputs that it controls, so using three wallets will show up as three controlling entities with blockchain analysis.  However, it will also reveal a lot of cross payments between these wallets, leading someone to assume they are somehow connected, possibly being controlled by the same person.

As for your other questions, as long as the addresses change for each transaction, so will the scriptPubKey and therefore the scrpitSig of the spending transactions.

Just remember, it's not the similarity of the scripts that allow blockchain analysis, but the association of the inputs and outputs.