Require some info about Tier 2 dependent visa

Hi everyone,

I will soon be making my application for Entry Clearance (Tier 2 General) and I intend to also apply for my family at the same time. However, my kids are in school and we plan allow them complete the current academic year and then join me later in the UK to continue from next academic year. My questions are as follows:

1. Can dependents collect visa and not enter the UK for up to 10 months?

2. After first entry to UK for how long must dependents stay before they can travel out?

3. After entry to UK for how long can dependents travel and stay out of UK?

I know that they can apply later at any time after my own visa is granted but I want to take care of everything now to avoid any mistakes in the process if application for my family is submitted when I will already be in UK.