Thanks for the feedback! However most of what you are requesting is already available on version 0.2.5 that is available here or on Patreon.
It currently features infinite days before the town battle in a true sandbox mode (if you do not advance with the main quest), the new format of quests (main and side). It also fixes the bug with the portraits you are mentioning and with some of the card capture bugs you are mentioning.
The not noticing the other cards and playing with silver, I understand that was a common issue too, I've changed the tutorial on 0.2.5 where it's shown to the player that he has a gold card already in the deck. I will however try to improve this UI as I know it's still far from optimal, thanks for the feedback!
For the card power creep it's something I'm defininitely trying to solve, I've actually launched a poll to see how people felt about it recently. For the next release I won't do anything about, but I plan to come up with a solution for the next releases.