VISA for parents

Hi,

I have secured a very good job in Australia, and I wish to move there with my family. For this purpose, I have already got 482 visa through my prospective employer and I expect to travel to Australia in August this year.

I kids have lived with my parents since beginning and I wish my parents to visit us once we are there in Australia to help settle down my kids there. I need your advice on below:

i) I understand I need to apply 600 visa for my parents which can be applied for any period of time up to 12 months. My parents have never visited Australia before and I want your advice what will be best time length I should apply or my parents visa i.e. 3 months, 6 months or 12 months. I want to reduce the chances of rejection that is why for the first time I want to apply for such a time period where chances to get the visa maximizes.

ii) At this moment, I got my 482 VISA but I am not currently in Australia. Based on this, can I invite my parents to Australia under visit friends and family stream? Is it advisable to do so or they should independently apply for tourist visa?

iii) What other things I should consider while applying for my parent's visa in the given situation? actually, my parents are old and retired and I don't want to bother them to go through all visa processing documentation rather I want to apply for their visa while I am in my home country and wish to get visa for them before I travel to Australia.

Thanks