Hi Paul,
Well I would advise you to use both. Unless you received you initial plants from someones Non-Co2 enriched tank the plants will always suffer trauma when submerged and will always have severe die-off if CO2 is not boosted. That's just a fact of life that we have to get over. If the lighting is kept low then in time, the plants that we mentioned will adapt to the low CO2 environment and will recover. Weaker plants, that require lots of CO2, tend not to regenerate quickly enough and never recover, especially if the light is too high.
When you do the dry start you will have grown more plant mass so you have a greater chance of having a higher population of stronger shoots and so there is more plant mass to work with which give you more margin.
Soil based planting has the advantage over a clay substrate in that the biological activity in an organic sediment produces CO2 as a result of the metabolic process of aerobic bacteria. Many of the plants we categorize as "low-tech friendly" are usually those that have a sophisticated root structure that allows them to uptake CO2 from the CO2 enriched sediment. Many people mistakenly think that the plants which have a very large root structure is because these plants feed NPK preferentially from the roots but that is not necessarily true. Large root structures are normally associated with plants which have the ability to use sediment CO2. So that's one of the advantages of soil. Another advantage of soil/compost is that it is usually high in nutrients, especially the more important ones like NPK. A disadvantage of soil is that it tends to emit ammonia into the water column. Dry starts solve this problem by having the biological activity in the sediment oxidize and convert the ammonia to Nitrate, which is not toxic, and which plants can use. Another disadvantage is if you are continually pulling up plants and rearranging them. This becomes messy with soil. Another issue is simply one of aesthetics. Normally you would "cap" or cover the soil because of the mess issue. You can use any decorative gravel to do that though, so that's easy to address.
For question 3, as mentioned, you can use soil or compost (John Innes 3 is a popular choice) which is the cheapest way to go, or, if money is no object, then ADA Aquasoil or the Oliver Knot equivalent are fully enriched, NPK+micro+peat clay sediments which are lovely to work with and which do not have the mess issue. Doing a dry start with either of these gives you the time to allow the ammonia to be oxidized and de-toxified. Now, remember, you are not limited to these popular sediments, but soil give you the advantage of the possibility of a clever source of CO2 plus nutrients, while the clay product like Aquasoil does not produce as much CO2.
The one to two months IS the dry start procedure. Troi has more experience and so he does not wait to have the sediment mineralized by dry start. He just goes for it. Although it is not an absolute requirement to do a dry start, Ammonia can be problematic. It can cause toxicity problems and can trigger some types of alga blooms. The dry start waiting period gives you a better chance of hassle-free success based on the reduction of Ammonia and to allow the plants to feed stress free and to produce more mass for the rainy day.
Water changes in a low tech system are not as manic because the growth rates are so much lower. The metabolic rate of non-enriched tanks are up to 10 times slower, so not as much organic waste and pollution is produced. Adding CO2 and high nutrient levels as seen in high tech tanks increases the amount of waste produced by the plants tremendously. You should not think of nutrients as toxic. They are not. It is the organic waste that plants produce that is toxic, just like the feces and urine produced by fish.
Cheers,
