Summary:
If סימנין דאורייתא, we return even a גט with סימנין; however if סימנין דרבנן we return a גט only with a סימן מובהק (and an אבידה with a regular סימן for הפקר בי"ד הפקר).
And let us be concerned, perhaps he wrote to give it in ניסן, etc. - וליחוש דלמא כתב ליתן בניסן כולי
Summary:
The חשש of שמא כתב בניסן וכולי is only when it is not known that the שטר was given later (we assume that it was given on time, either because there is no evidence to the contrary or that it is done in secrecy); however when we know the שטר was given after the date, there is no חשש.
When did the Get come into your possession - אימת מטא גיטא לידך
Summary:
It is only by a גט שנפל that the לקוחות can claim אייתי ראיה אימת מטא גיטך לידך (since it was אתרע), but not by other גיטין (which were not lost).