A. Can we use previous Monero Subaddress (not the last)?.
You can reuse addresses but it makes no sense to do it, especially not with privacy coins like monero.
B. does any money that received on any subadress will forwarded to main account? or only the lastest?
You can move it manually and send to newly generated address, but I am not sure how exodus wallet is managing this.
I would stop using this closed source wallet and switch to open source alternatives (Feather, Stack wallet, Cake wallet, Trezor HW, etc.)