Thank you!
It's certainly possible to travel between worlds, although the practice is almost entirely unknown. In any case, it's easiest to travel between worlds which share similar laws of physics (in other words, which share the same edition). In fact, I'm aiming to start a campaign next year for my best friend, which will take place in one of my 3.5 settings, and at some point his character's quest will lead her to another of my 3.5 settings. Crossovers are also semi-common in the fiction I've been writing based on these worlds.
Since each world is basically in its own universe, each one has its own sets of these basic planes. There may be a few demiplanes which are shared between all universes, and even some planes which defy the laws of being a part of any universe; the Kaiju Dimension, for example, is a plane which is not locked to any universe, but which may still occasionally connect with any world in order to allow the passage of kaiju to and from that alien realm.
Well, any psionic-based class is able to directly affect the Mindscape of others, and indeed the power of Psi magic itself is drawn directly from the Mindscape of whomever uses it. So if you play a psion (renamed "esper" in my settings), you're already fully-equipped to mess with the minds of your enemies!
Well, gnomes rarely refer to themselves as simply "nom". Instead, all gnomes have specific names for the three subraces: Chromanoms for the brightly-coloured-haired forest gnomes; Glimmanoms for the metallic-hued-haired rock gnomes; and Undanoms for the monochrome-haired, Subterrene-dwelling deep gnomes.
However, one of the major characters of the series Crystals of Silveria is a gnome bard whose full name is Broccoli "Brocc" Choy Verdann Svetlana Asparagustus (and at least 20 other middle names) Farshot, and he often makes references to food or eating. One of his counterparts in the upcoming series Shell of Thal, another gnome bard known simply as "Sven", is the only member of his ship's crew who actually enjoys the cook's bland food, and scoffs whatever his shipmates don't eat in a few seconds flat. Yeah, there seems to be a running gag of food-obsessed gnomes in my series...