My first tip would be don't fall into the trap of thinking you need all these miracle products, the only thing that will do is put you in debt. All you really need is good, healthy, nutrient rich soil with a complete soil foodweb. Me and a lot of people achieve this by merely topdressing a couples inches of compost annualy, while keeping your gardens mulch(mulch breaks down into compost and fertilizer). You dont need any expensive product in a bottle, what you need is good homeade compost and mulch. A soil test will tell you if you need to add anything, but i would just an inch or two compost and mulch until you get the results of the soil test. The test will tell you to add synthetic fertilizers(non organic) for whatever you are deficienct in(if even anything), you dont have to add those synthetic fertilzers though, you could go with organic alternatives. For example, instead of usong STEM(Soluble trace element mix) you could use azomite(crushed rock, or kelp seaweed). Your question about fertilizing seedlings.. Seedlings dont need fertilizer until they are around a month old. If the seedling is in your gardens mineral soil(sand,silt, clay), then your seedlings definetely dont need fertilizer, they can obtain it from the soil. How do you think nature grows plants, she arent spoon feeding it chemicals, she is merely dropping leaves, and other organic matter on a continuis basis. I try and imitate that for my garden. Neem oil is an organic alternative to other harmful insecticides, etc. i never used it, never needed it. But, some people really like it.. I would always go with a less toxic, safer alternative than glyphosate and stuff like that.. Dont get fooled into buying all these products, all you might need is a little compost, leaves, and hard work! Get a soil test to rest assured, and look for organic alternatives to the products the soil tests tells you. It's really that simple! Don't get overwhelmed! Best of luck!

I would suggest 1/4 to 1/2 the recommended strength MG 15-30-15 every 2-4 weeks. Wish that I could give you exact figures, but most or many of us that container grow with artificial fertilizers do it by 'ear' or perhaps 'eyeballing' describes it better. You will learn by experience how to read leaf color etc for how often to fertilize. It is in my opinion much better to err on the side of under-fertilizing. Put in a larger pot to start with. Try to disturb the root system as little as possible. I would go to a one gallon container or at least half that.

you want to use the same sealer that he used. cross mixing say A water and solvent based product is not A good idea even if these have a years wear on them.... when you maintain and seal its smart to always stay with the same product . we use miracle 511 pourus plus for travertines.

No one can offer meaningful (to you) advice about fertilizer frequency for your specific application without a good idea of of what you're growing in and your watering habits. E.g., if using a water retentive soil that you have to water in sips to prevent over-watering, once per month might be adequate, If you're using a fast-draining, well-aerated medium you're flushing at each watering, once per week might not be enough. I use Foliage-Pro 9-3-6 with a fast draining mix and fertilize weekly (when temperatures are favorable) at well beyond recommended full strength in the summer. In winter under lights, I fertilize at every watering, using 1/4 tsp per gallon of water, making sure the pots are flushed as I water. There is no way of knowing if this is appropriate for your situation w/o more info, though. Al