Commentary on Poem 1

Furi et Aureli, comites Catulli,
sive in extremos penetrabit Indos,
litus ut longe resonante Eoa
tunditur unda,

See Furus and Aurelus are mentioned in other poems by Catullus. He seems to have not liked them very much and been in compitition with them for lovers.
The word comites seems to imply that Furus and Aurelus were in the same militery chors as Catullus
This stanza and that which follows sets out the boundries of the Roman World India in the east to Arabia and Africa in the south east to Parthia in northeast to Brittan in the northwest.

sive in Hyrcanos Arabasve molles,
seu Sacas sagittiferosve Parthos,
sive quae septemgeminus colorat
aequora Nilus,

sagittiferosve refers to the Parthians favorite mode of battle with arrow from horseback.
septemgeminus refers to the fact that the Nile had seven mouths.

sive trans altas gradietur Alpes,
Caesaris visens monumenta magni,
Gallicum Rhenum, horribiles vitro ulti-
mosque Britannos,

All of the places listed abouve are hot spots where the Roman army would have been.

Lines 13-16

Lines 17-20

Lines 21-24