Unless you can use an exchange to buy Lightning Bitcoin directly so they open large channels instead of having users open small channels, but that means you can only use custodial wallets.
Not necessarily, the Eclair wallet provides for buying inbound capacity. I think the Zap wallet has a similar function.
If part of that purchase was (example) you paid for an inbound 0.05 channel and part of that 0.05 was sent to you (say 0.04) your cost might be (random numbers out of my head) say 10% on top of the 0.04 plus the TX fee to open the channel - rounded up to 0.005. In the hypothetical example you might pay (in advance) 0.045 and get a 0.05 channel opened to you with 0.01 inbound plus 0.04 outbound capacity which would no doubt be a healthy start to any new node.