Hi JustAnAnvil and welcome. These are interesting questions and you are likely to get a number of different answers to some of them.
1. The bucket or carboy you use for active fermentation (the first few weeks) is typically referred to as the primary fermenter and that fermenter does not have to be sealed and typically will have a significant amount of space (headroom) above the surface of the liquid. This to take care of any froth or foam caused by the action of the yeast AND to allow the yeast at this stage access to needed oxygen. Too little O2 at this stage can cause the yeast to produce hydrogen sulfide and that smells like rotten eggs.
2. When you rack (transfer) the wine from the primary to the secondary the colony of yeast should be much greater in size than the colony you pitched (added) so there is no need to add yeast. Also at this stage (typically, if we are talking about wine and not say, cider) the yeast cannot absorb any more nutrients so any you add will be a haven for volunteer bacteria. And that's not a good idea. During the next few weeks in the secondary the wine is not in fact "aging": the yeast are still active but they won't have much (or any) sugars to ferment. Nonetheless they tend to remove all kinds of compounds they have produced and the effect of that is to enable your wine to continue undergoing all kinds of flavor and other changes. With red grapes, for example, there may be what is called MLF (malolactic fermentation where malic acid is converted into lactic acid and the sharpness of the malic smooths out. This happens with apple cider too.
3. When to add fruits and other elements such as oak is really a matter of one's style in wine making and one's preferences. Certainly, adding any element to the secondary means that you are using the alcohol to extract flavors rather than water and while water is a great solvent alcohol is more powerful. Folk often argue that tastes are "fresher" when fruit is added to the secondary and certainly, you often have significantly more control when you add say, oak to the secondary rather than the primary as you can far more readily rack the wine off oak or fruit in the secondary when you think that the right amount of flavors have been extracted than you can in the primary (if the yeast is still very active you may not want to rack your wine as you will likely leave behind a large part of the colony and that just might inhibit further fermentation in the secondary.
If I were you , I would make a couple of experimental batches - single gallons perhaps and add the key materials to the primary in one batch and to the secondary in the second batch and compare the differences , though smoked tea suggests that you need hot water to brew tea whereas you might want to avoid heat when making wine with fruit (not least to prevent you from setting any pectins - you are after all making wine and not jam.
Good luck
