Re: How to understand these transactions all using the same address?
So your solution now, is to "combine multiple UTXOs from multiple addresses as inputs" LOL 
how do you know if the wallet used is able to do that first?
Yes. Every half decent wallet does this automatically. If you are using a wallet which can't combine two UTXOs from different addresses in the same wallet in to one transaction, I suggest you change wallet. No wonder you have problems with dust if this is the case. how do you know if the wallet used is able to do that first? Do you know some wallets on smartphone offering this feature?
Pretty much all of them.Do you really think people want to do this kind of trick for each transaction they are sending? Are you doing it yourself?
They don't need to. The wallet should deal with it all automatically.Which wallet are you using that can't handle more than one address without creating dust?