So I heard lymohoma can cause completely normal blood work. Wbc can be normal. Is this only for stage 1 and 2. Stage 4 would cause something in bw?

Not simple to answer. Early lymphoma may have normal blood counts, so may untreated advanced lymphoma. However in advanced lymphoma the bone marrow will be affected by the treatment and it is usually not practical to separate the changes due to tumor from those due to treatment. Generally there is decline in all cell types.
That depends... on the type of lymphoma. Certain low-grade lymphomas (i.e. Chronic lymphocytic) have very classic peripheral blood findings and these findings aid in the diagnosis. Many others, including many higher grade lymphomas, rarely present in the blood and are diagnosed by biopsy of a lymph node or involved organ. Hope this helps!