Sale packages and gem sales

I’ve been above 10k gems since I was about level 70 so I havnt done any other deals except starter package and 3 workers. 

I wanna know which of the deals are repeatable. Like unit pack, spell pack and 5 levels pack. Is it possible to do them multiple times?

Also as soon as I dropped down to 300 gems instantly got a gem sale of 31%. I never bought gems before,  if I buy any of the gems on this sale will I lose this offer forever? Many of my alliance friends says they havnt seen the gem sales for at least 6 months except the weak christmas 20% offer.

I am level 106

Now I got a 48% gem deal before the timer on the first expired 

The starter package is repeatable, you have to have well below 500 gems, including uncollected quest rewards. I have spell and warrior package (+5 levels), never got them again.

Ok thanks for information.

Yesterday I got offered a unit pack but one of the units I had equipped was being upgraded so it would only give me two upgrades intend of 2. So I let it expire.

Is there any fixed timer on how long until a new deal appears? Some in my alliance said it was 48 hours before but not sure if it’s been changed. 

What about gem sales? I got a 3 hour 50% off sale, then instantly a 50% more gems for 24h. If I buy from any of these will it be gone forever also?