1.) A "Standard" (Canon) IG Infantry company is approx 300 men (OW: No surrender pg.30). This consists of six Platoons each consisting of 3 Infantry Squads, 2 Heavy or Specialist squads and 1 Command squad (Approx. 50 men total). Pretty much right out the Codex: Astra Militarum there! So yes, there is a Canon number.
100-150 men and gear. Ciaphas Cain series, Gaunts Ghosts Series, Penal Legion series, pretty much any of them that use real world numbers for troops. IIRC Epic and Planet Strike also used this range.
2.) A SM Strike cruiser is much smaller than you suggest! It is a light cruiser (Similar to the Lathe class cruiser in ITS). It supports a single company of Astartes with all their vehicles. In BFG It could support 2 squadrons of small craft and mounted a Bombardment cannon in a Dorsal mount. In Rogue trader this would translate to a Jovian pattern Escort bay and a Bombardment cannon dorsal mount as well as a Storm drop pod bay (Which would theoretically allow the entire company to be deployed in a single salvo!). In current Background, The squadrons held on board the launch bay would probably include a Thunderhawk squadron, A Thunderhawk Transport squadron and an Aeronautica Squavdron made up of a mix of Storm Ravens and Storm Talons. (I think Baronlveigh was actually thinking of the Battlebarge.) I actually came up with a pretty close approximation of a Strike cruiser using the Lathe class as a template!
On the Olympia class light cruiser (aka the SM Strike Cruiser)
LB strength translates 1 for 1 between BFG and RT, so that's Str 2 or a Jovian pattern Landing Bay. The bombardment cannon is actually called the 'prow bombardment cannon' in BFG for a reason. In fluff it's occasionally swapped for a lance. Certain Strike cruisers have also fit launch bays, torps, and the bombardment cannon simultaneously, (See Ultramarines novels) though this variant may be unique to the Ultramarines (who, despite their normally conservative view, get almost as heretical as the Dark Angels with their ships) and Imperial Fists. SCs can also swap their LBs for str 6 torps.
Armor translates out to something like 25 all around at minimum, with speed around 7. They would automatically get a teleportarium and drop pod bay. It also supports chapter serfs, and contains training facilities, etc.