Answer to question 1: I believe it's in your best interest to hire a Realtor (different than a real estate sales agent) to represent you when purchasing a new development condo. They're going to get notices of buyer incentives and newly released apartments from the developer; and depending on the market, they can negotiate the closing costs and price for you, etc... Formalize the working relationship by signing a Buyer's Broker's Commission Agreement (or something similar) and make sure your Realtor is legally obligated to work for your best interest in the transaction.
Answer to question 2 & 3: You can ask the condo building's sales office for their policy in this situation. Email them, directly, and ask them for an answer in writing. Most new condo developments offer a buyer's broker commission. Generally, a buyer walking into a new condo development (without their agent), must register their agent before or upon the first viewing/showing. If this doesn't occur, I know of quite a few developments that decline to pay for the buyer's broker's commission. Personally, in this situation, I register my buyers - as I make the appointment for the viewing - confirm the appointment the morning of viewing and attend the viewing/showing with my buyers.