Yes, iTel S41 runs on the latest Android 7.0 and thus having support for the multi windows operations.
Yes, iTel S41 does support gesture controls.
iTel S41 dimensions are 144 x 72.4 x 8.3 mm.
Yes, you can use 2 different WhatsApp accounts in iTel S41. Not only that, you can use 2 different Facebook, Instagram and Twitter accounts as well.
No. iTel S41 does not have a hybrid sim slot. It has 1 dedicated slot for MicroSD card and 2 dedicated sim card slots.