316 is better. Sink generally cannot go too wrong, but do be aware of no name cheapo so called SS 304 that is actually made from cheapo grade that still rusts just by looking at it.

Undermount or top mount, the former is harder to do maintain as the silicone can and will grow mildew over time. Top mount easier to maintain and install in comparison, but aesthetic wise lose to undermount.

The choice of tap is important. I went and bought ikea tap instead of reusing a dismantled teka mixer, technically new from developer that my friend was remodelling and donated to me. that one keep on leaking and dripping into the cabinet. Ikea one super easy to install and come with very long metal flexi hose for the water inlet, properly gasketed and doesn't leak at all.