Immigration to Australia from the USA for a partner

My husband and I met online around 10 years ago but never met in person until late June this year. We married in mid-July and I left the states about 2 weeks after that to return home. We are trying to get him here, and it is particularly hard as I have Bipolar disorder which puts a lot of strain on me, as well as I am the one preparing his application.

We want to know that if he comes here for a visit and actually decides that this really is where he wants to stay, is it possible to apply for the partner visa from here? As it stands now, we are toying with if I will move there or he move here, as the costs are relatively the same. I am aware that it is frowned upon to do it this way, but if he likes it here, why should we have to send him back, just to apply, and not see eachother for 12 months or more?

Also, there seems to be very unclear instructions on the immigration website. For example, the 'checklist' says not to do a medical until requested by the immigration agent, yet when I called to ask them about it, they said that it would speed up the process to have it done before applying. Does anyone know the answer to this?

Also, I have been toying with the idea of using an immigration agent, either for me to get there or him to get here, has anyone had a positive experience with them? Or is it ok to not use one? I read on one site that "not having been in each-others physical presence for long" can affect the application, and we were only together physically for 6 weeks, although we have known each-other for 10 years online and kept in contact that whole time.

Im not liking that it will take 12 months for him to be approved if he applies overseas and Im not sure how one would apply when being here, as it seems rather vague as to how this happens..... its all confusing me so much!!

Any help is greatly appreciated.

THanks in advance.