hi ranlo,
Thanks a lot for your proposal. Actually the feature you want is already available

In the Strategy page, if you open the Expert mode you will find a setting called : Keep amount. This setting will block lending under a certain threshold of your balance.
Holding back a % of your balance could be an interesting improvement (thanks!) even if we think that its very important to keep strategies as simple as possible for a better usability and user experience for the moment.
Regarding swapping funds between wallets, it would require to add specific rights in the exchanges API. For the moment we are dedicated to creating margin lending offers on your behalf. We are very cautious with any other API rights.