From my experience, one of the most useful tools for an artificer is a Dedicated Wright (ECS p. 285). Get one of these and carry it around in a cart, or later a portable hole or something, and it can build stuff for you as you adventure. The Exceptional Artisan feat cuts the time by 25%, but personally, I'm not a fan of it, as the Wright covers most of the issues here.
For divinations and knowledge... Well, you're an Artificer. At level 6, you get Craft Wand as a bonus feat, letting you begin to make eternal wands, which are amazing for this. An eternal wand of Augury costs 5,695gp, if I did the math right, so you can make it for 2,847 gp and 5 sp in a little under six days. After that, you've got a 2/day "is this a good idea?" stick. Note that since you don't actually cast arcane spells, you will need to roll Use Magic Device each time you want to use one. However, because these are mostly out of combat things, you should probably be fine unless you roll a 1. If you want to take 10 on that, there's a feat in City of Stormreach (Hardened Criminal, iirc) that lets you pick a skill to always be able to take 10 on. Requires Iron Will.
The Oracle domain gets Divination as a 3rd-level spell, so you can make one of those as well (base price 12,150, so you're spending 6,075gp on it). You now have about the same amount of divinations as an equal-leveled Cleric or Wizard who's spending slots on it.
For knowledge, make an eternal wand or two of Guidance of the Avatar for 2,210gp each. Put cross-class ranks into the important knowledges and use your presumably-good Int mod and the +20 bonus to learn about the enemies you've divined with the other wands.
For detecting and preparing for an encounter, note that a lot of things are useful to have in general, even if you're not sure if you'll run into stuff. Scrolls of general-purpose answers like Banishment or Dismissal are good if you think you might end up fighting outsiders (and once you reach the level you could make them, that's a good bet for the near future outside of themed campaigns). Summons are also very useful. Make scrolls of Lesser Planar Ally for 600gp each, and then pay another 100-600gp or so to whatever you call for some sort of useful SLAs. Summon Nature's Ally IV can nab you a unicorn for the same price as a scroll of, say, Neutralize Poison, and it can also heal and temporarily turn off mind control effects. There are a lot of really good, open-ended spells to make scrolls or wands (or eternal wands) out of. You have access to all of the spell lists, and you can make stuff very fast with your Dedicated Wright.
The biggest issue I see is that, as you said, at later levels, the DM might not give you downtime. Having a Dedicated Wright is all fine and dandy, but it still takes time to make stuff. One solution to this might not fly in every game, but if you're trying to build a tier 1 artificer, you're probably already in a high-op campaign. Find (or make, once you're level 15 and can craft a scroll of Genesis) yourself a fast-time demiplane, and do your crafting there. Alternatively, if you're in Eberron, plane shift to Dol Quor and set up a base of operations there. It's got a 10:1 time ratio, and unlike Dream from the Manual of the Planes, it doesn't break anything you make there when you leave.
If you're not able or willing to plane-hop for more time, there's always an even cheesier method: self-resetting trap of Time Stop. Costs 76,500gp and 6,120 exp to make, and triggering it will give you as many rounds of effective time as you like, because Time Stop doesn't actually stop time, it just speeds you up. Nested Time Stops would just stack each one inside the first round of the previous, allowing you to get lots of time to craft at super-speed, then rest up and be ready for whatever you're doing. Heck, you could even go get new raw materials by robbing a bank or wizards' tower or something while sped up. This method is exceptionally silly, though, and really falls into the realm of Theoretical Optimization, so I suggest against it.
Also, it occurs to me that I didn't address your first question. My suggestion for that would be to first figure out what sort of artificer you're going to be. You might be someone who does lots of buffing through items, in which case, the Metamagic Item infusion combined with a wand/scroll/staff/eternal wand/minor schema is really good. Metamagic Item for Chain Spell and Persist Spell on a buff spell like Polymorph, anyone? Suddenly everyone is a hydra, or something. I like Minor Schemas (Magic of Eberron) for this, because you only need it once per day, and it's a 1/day scroll of whatever you like. If you're being a blasty artificer with Metamagic Spell Trigger, then your feats would be focused on that, etc. I have not actually played an artificer in a game, so I'm a bit unqualified to give advice on the actual build stuff.