Vikrant, is the picture taken from the front of your Entry door? I love your style and pieces. Just a few suggestions if this is the view when you first step into the foyer, I am not an expert! Ganesh in the place of the mirror to greet you and your guests as Goddess Lakshmi is supposedly behind him, will create more prosperity to the household. A recessed focal light from the ceiling to highlight its beauty. Another silver empty frame placing behind Ganesh, similar to the mirror to frame the idol or a Rajasthani silver jali work piece that way the wall behind would not look empty either! The beautiful mirror can be placed where you have the Ganesh now, that way the positive energy coming into your house does not get bounced back or out...

Fungus? Like mold? If so, perhaps try bleach, or taking out the wood and using something else. Fungus/mold in a restaurant is definitely not a good thing.

The wood has to reach what's called Equilibrium Moisture Content (EMC), which is different for various areas of the country/world. I don't know about end grain slabs, which is what you have, but the rule of thumb for lumber air drying (vs. kiln drying) is 1 year for each inch of thickness. Moisture leaves the end grain faster than the side and/or edge of the boards, so in your case the drying time will probably be shorter. If it is not dried in a controlled environment your slabs are going to split radially, due to drying too fast.

It totally depends upon your interior theme. Now a days polished cement floor is in as it gives quite a raw look and you can go for some combination of glass mosaics with it. Else you have so many options readily available in the market.