Just to tie up loose ends.
In your #4, Dan, εν ᾦ χρόνῳ λέγω σοι is not “over time” but “while I’m speaking to you,” “in the course of my speaking.” εν ᾦ χρόνῳ λέγω is short for the more cumbersome εν τῷ χρόνῳ ἐν ᾧ (lit. “in the time in which I’m speaking to you”). Rouse’s schoolboys are meant to understand him as he’s speaking.
—But in giving you these answers, complete with translations and grammatical explanations, I think we may be running counter to Rouse’s pedagogical method, which is essentially oral and meant to be self-explanatory. It’s inductive.
δῆλον οῦν δή πού εστι, δια τί λέγω πολλάκις ἕκαστα “So I guess it’s clear why I say everything many times over.” (“I guess” is often the best translation of enclitic που. δή intensifies δῆλον. διὰ τί is “why”, lit. “on account of what”. ἕκαστα each of the various things that I’m saying; “each of these things” would be ἕκαστον τούτων.)
In your #2, ᾶρα νῦν δῆλον ὅ τι εστι λόφος: the ὅ τι (sometimes written ὅτι as one word) is the indirect (not indefinite) form of τί, “what?”. The clause ὅ τι εστι λόφος is an indirect question.
Cf. τί λέγεις; “What do you mean?” versus δῆλον ὅ τι λέγεις “It’s clear what you mean.” (This could also use the direct form, δῆλον τί λέγεις, cf, διὰ τί not δι’ ὅ τι above).
In your #1, τις καὶ ἄλλος is just “someone else too” (not “even”). Here ἄλλη not ἄλλος, so female.
I don’t say anything about the accents, but you might find them puzzling if you’re not aware of how enclitics behave, particularly enclitics in series. (And Rouse is not entirely consistent here.)
A final note. Particles, such as που and δή, and γε earlier, both single and in combination, are one of the glories of ancient Greek, especially Attic Greek. They’re often untranslatable (which is not to say meaningless!), or overtranslated or mistranslated, for in English we tend to express equivalent semantics by intonation alone. One of the good things about Rouse is that he uses them idiomatically. The significance of word order—much more flexible in Greek than in English—is also something that’s difficult to capture in translation. So the aim is to learn to read without translating, since translation inevitably interferes with accurate understanding.