Congratulations on your offers! I recently responded to a similar thread. Since your ultimate goal is to study law, you should enrol in the program that allows you to study law. In your case, you received an offer for WSU's Bachelor of Social Science/Bachelor of Laws, which provides you with that opportunity. The reason for this is that when attempting to transfer, students must consider the possibility that their transfer may not be approved, no matter how insignificant it may be. Based on this, if you enrol in the WSU program and end up not succeeding in transferring to UTS's Bachelor of Laws, you will have at least guaranteed that in the worst-case scenario, you would still be able to study law. Of course, while it is definitely possible to transfer internally from UTS's Bachelor of Communication (Social and Political Sciences) to its Bachelor of Laws, failure to do so would leave you unable to study law.
Additionally, recognition of prior learning may be relevant to you. If you transfer internally to UTS's Bachelor of Laws, you will have to start this degree from the beginning because you would be transferring from a completely different degree. On the other hand, if you transfer from WSU, you may be able to have some of the law units that you complete at WSU recognised as prior learning, meaning that you may not need to start the equivalent degree at UTS from the beginning.
In terms of your other question, the answer is yes. You can transfer either to UTS's Bachelor of Laws (which is a single degree), or one of many
law double degrees that UTS offers.
I hope this helps!