EEA Family Permits for Mother and Sister

[profindar]

I am EEA National who has been residing and working in the UK for more then 3 years and currently earn not less than £30K/annum.

I wish to invite my dependent mum and sister (aged above 22) to the UK under the EEA Family Permit route. They are both not currently working and I primarily support them financially.

I want my mum to come at first for 3 months but want the possibility for her to be coming yearly for medical check-ups and visitation.

For my sister who is a recent graduate, I want her to come, live and work here in the UK.

Please also note that I have my own mortgaged property (3 Bedroom House).

Please advise on the following:
• Can I invite both of them together so that they can both travel to the UK at the same time?
• Do I need to have substiantial ammount in my account? Like how much?
• In the application, what should they put as their main purposes of visit?
• What should they put as their length of stay?
• What other advise can you provide?

Here are the documents that I intend to give them for applications:
• Certified copy of my EEA Passport Photopage
• Copies of recent payslips
• Copies of PAYE Income Tax Summary
• Bank Account Statements
• Mortgage Letter and Statements
• Council Tax Bill
• Copies of HM Land Registry Property Register
• Property Completion Letter and Statement
• Utility Bills (Energy and Water)
• Phone Call Activities (VoIP Calls)
• Past Pictures taken together

Thank you all in advance for sharing your experience and advice.