U233 is definitely fissile and can be used in bombs as well as nuclear reactors. The problem with it is its half life of 68 years which means uranium stored will continuously get depleted quickly. And it is more riskier due to higher chance of auto trigger.
U233 is not even 1% lighter than U235. This difference in weight is insignificant compared to the disadvantage U233 offers. A nuke made of U233 will not detonate after 10 years as 15% would have been depleted due to short half life. No one likes to use such material.
India is not reliant of USA or NSG to extract its Uranium indigenously. Indian Uranium is free from any restrictions and can be used as per Indian will
45 is not enough. We not only need high quality submarine but also large numbers of them. In war attrition rate is something one must consider. To be able to quickly make up losses, low cost submarines are also needed
In my opinion, we don't need submarines in large numbers but a right mix of them and better at sea time per submarine using 2 crews per submarine
I personally feel that 21 diesel electrics and 12 SSN with more nuclear boats to eastern side then the west, should be more than enough for taking care of all the mission profiles.
Indian naval fleet needs to be an overall balanced one and not be under sea heavy or carrier heavy kind, just balanced