Purchasable store items, questions.
Bag slots are per character.
The unlimited harvest tools are account bound, but you’ll have to move them from character to character.
Home instance items are available to all of your characters, and they can be harvested once per day per account.
I feel the copper-fed salvage item is definitely worth it in the end. The silver-fed one, not so much. And the home portal stone is worthless, to me, as I can already get to a home instance for free.
Bag slots are per-character, not account-based. So you’d have to buy them on each of your characters.
Harvesting tools are one single item, so only one character can have it at a time. However, they are account-bound (now, they used to be soulbound back in the day) so you can pass it around to other characters via the bank if you like. Which may or may not be a huge hassle depending on how often you swap your characters around.
Home instance nodes are account-wide, so any character you have can access them (for that matter, you can invite other players into your own instance and they can use them that way as well). However, you can only harvest them on one character per day.
The worth of the portal stone and salvage items is mostly personally determined. For myself, I don’t see much use for the home city portal, as I usually have at least one character in a city that I can do my daily home instance harvest run with and there’s not much reason to go there otherwise. I did buy and love my Copper Fed Salvage-o-Matic, though. Like the harvesting tools, its one single item (so can only be on one character) but account-bound and can be passed around at will. That said, I tend to just keep it on one character, then pass over all my loot to that character to salvage. Well, at least all my champ bags and other loot bags (like the ones you get from the Silverwastes). When you’re salvaging hundreds of items, its a nice little convenience to not have to stop and select a new salvage tool every 25 uses or stop to buy more from the vendors. That is pretty much the entirety of the use of the item though, convenience. You save a very small amount of copper per salvage using the Copper-Fed salvage kit compared to buying basic salvage kits, but its such a small amount compared to how much gold you’d be spending on buying it in the first place that it would take astronomical amounts to even break even.