B737-300 FLC HAS RWY INCURSION AT HOU.

Narrative

WE TAXIED TO RWY 4 VIA TXWY H. XING RWY 17/35; WE WERE SWITCHED OVER TO TWR. THE CPR RAMP WAS BUSY; SO I WAS BEING CAREFUL WITH MY TURN OFF OF TXWY H TO HOLD SHORT OF RWY 4. TWR CALLED AND ASKED IF WE WERE MONITORING. WE SAID YES; THEN TWR CLRED US FOR TKOF AND ISSUED A TURN. WE ACKNOWLEDGED AND RAN THE BELOW THE LINE CHKLIST. FINISHING UP THE CHKLIST; I SCANNED FINAL AND SAW AN ACFT POP OUT OF THE OVCST. THE ACFT APPEARED TO BE TOO CLOSE TO THE RWY FOR ME TO SAFELY MAKE THE TURN ONTO RWY 4 AND TAKE OFF. I STOPPED. WE TRIED TO CALL; BUT THERE WERE 2 XMISSIONS FROM OTHER ACFT BEFORE WE COULD ALERT TWR TO MY DECISION TO STOP. I HAD STOPPED ABOUT 5-10 FT BEYOND THE HOLD SHORT LINE. TWR WAS NOT PLEASED AND HAD US HOLD OUR POS. TWR ADVISED THE LNDG ACFT OF OUR INCURSION OVER THE HOLD SHORT LINE. TWR THEN CLRED US ACROSS THE END OF RWY 4 ONTO TXWY G TO TURN AROUND. THERE WAS AN ACFT 'S-TURNING' ON FINAL TO PROVIDE SPACING WITH THE ACFT WE INITIALLY STOPPED FOR CLOSE BEHIND THE INITIAL ACFT. WE AGAIN WAITED FOR OUR TURN AND THE SUBSEQUENT TKOF WAS UNEVENTFUL. WHEN WE WERE INITIALLY CLRED FOR TKOF; TWR DID NOT ADVISE US OF TFC ON FINAL. THIS INFO WOULD HAVE BEEN USEFUL IN MY DECISION MAKING PROCESS. WHEN I SPOTTED THE TFC ON FINAL; IT WAS DIFFICULT TO IMMEDIATELY DETERMINE IF IT WAS A SMALLER ACFT REALLY CLOSE OR A LARGER ACFT A BIT FURTHER AWAY. I REACTED INSTINCTIVELY IN STOPPING. THEN WITH A LITTLE MORE TIME THE SMALL PLANE/LARGE PLANE QUANDARY BECAME CLRER. HOBBY TWR ALWAYS DOES A GREAT JOB; BUT I FELT I HAD TO STOP ON THIS SIT. A FLT CHK ON CONFLICTING RWYS WAS IN PROGRESS AT THIS TIME ALSO.