Do you have a resolution to
1) & 2) You need to check the changes page in order to find if there is a symbol change. US/CHANGES1 page will provide you a list of US stock exchange information and in specific for NYSE it will be NYS/CHANGE2. Foe entire universe you can refer to WORLD/CHANGE1.
3) You can search financial statements for a company using RIC or REPONO. On TRKD API search you can use search service i.e., ISSUEISIN to RIC & REPONO with primary RIC fitler as an addition.
Also there is no NASDAQ A or B. We have exchange code .OQ for NASDAQ specific exchange code or .O which is NASDAQ consolidated RIC which gets values from different regional exchanges of US