Hi and thanks for the question and email as well...I checked for the "Mark This Forum Read" functionality (which I don't personally use) in the mobile version and it does not appear to be there unfortunately...If someone knows where it is (if it does exist), please post and let us know!
As for everything being so tiny...I frequently visit the mobile site on my iPhone using Safari and the text seems very readable to me...Can you try another mobile browser or enlarge the text via Firefox settings? I wonder if you're actually looking at the full site on your iPhone, in that case everything would appear tiny...To switch to the mobile version, scroll down to the bottom of the page and there is a drop down menu (near "Contact Us")...Select "Default Mobile Style" and the mobile site should load.
I can confirm that the mobile version of the new platform we're moving to does indeed have a "Mark read" function clearly visible above the thread list...It also has a "Watch" feature as well.